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Abstract:

The present invention is directed to processes and business methods and
wastewater treatment units for converting the waterborne residuals from
wastewater generated by food processing plants into an ingredient
suitable for use in animal feeds. The ingredient produced by the
processes of the present invention has a high protein content and can be
used as a replacement for conventional sources of animal feed protein
such as fish meal.

Claims:

1-44. (canceled)

45. A composition comprising: a dried and deactivated bacterial mass
comprising a mixture of bacteria, wherein the true protein content is at
least about 50%, wherein the dried bacterial mass is suitable for use as
a feed for animals used for human consumption and complies with the
requirements of the American Association of Feed Control Officials
Official Publication (2007).

47. The composition of claim 45, wherein the crude protein content of the
dried and deactivated bacterial mass is about 60% or greater.

48. The composition of claim 45, wherein the dried and deactivated
bacterial mass has a Vitamin B12 content of greater than about 5.0 mg/kg.

49. The composition of claim 45, wherein the dried and deactivated
bacterial mass has a true protein content of greater than about 55%.

50. The composition of claim 45, wherein the dried and deactivated
bacterial mass has a pMC value of about 90 or more.

51. The composition of claim 45, wherein the protein/ash ratio of the
dried and deactivated bacterial mass is about 6.0/1 to 8.0/1.

52. (canceled)

53. (canceled)

54. The composition of claim 45, further comprising carbon compounds from
sources selected from the group consisting of vegetables, fruits, and
sugars.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application
No. 60/984,653, filed Nov. 1, 2007, which is incorporated herein by
reference in its entirety for all purposes.

FIELD OF THE INVENTION

[0002] This invention relates to a process for preparing a proteinaceous
animal feed or animal feed additive from microorganisms grown in
wastewater streams containing organic matter, a wastewater treatment unit
for carrying out the process of the present invention, and business
methods therefor.

BACKGROUND OF THE INVENTION

[0003] Commercial food supplies for animals (e.g., birds, fish, cattle,
etc.) consist of nutrients (e.g., protein, vitamins, minerals, fats, and
carbohydrates), for example raw ingredients or food additives that may
include whole, unprocessed food materials (e.g., meat or plants),
marginally processed foods (e.g., fish meal, soy meal, nut meal, etc.),
and waste by-products generated in the production of other food (e.g.,
wheat middlings, bone meal, blood meal, feather meal, etc.). One of the
main motivations for employing alternative food additives in feed
formulations is to reduce the cost of the protein component. Fish meal
provides a common source of protein for animal food, particularly in the
aquaculture, pig, poultry, and pet food industries. However, there are
many drawbacks to the use of fish meal as a food additive. The continued
growth of the demand for fish meal from global aquaculture operations
places excessive strain on world fisheries, and may deplete wild fish
stocks due to over-fishing. Several recent scientific journal and popular
media articles point to an emerging consensus regarding decreased
landings of wild fish, and the potential impending collapse of
economically and ecologically vital fish stocks (see for example Watson
and Pauley, Nature, vol. 414 (2001), pp. 534-536; Myers and Worm, Nature,
vol. 423 (2003), pp. 280-283; and Special Report: The Global Fish Crisis,
National Geographic, vol. 211. no. 4 (2007), pp. 32-99). In addition,
seasonal fluctuations and meteorological events (e.g., El Nino, La Nina)
influence market prices for fish meal.

[0004] Alternative by-product protein sources (such as bone, blood, and
meat by-products) have been used in animal food industries in an effort
to reduce reliance on fish meal as a protein source. However, there are
concerns that such protein sources may compromise animal and human
health, for example by causing the spread of "wasting" diseases, such as
bovine spongiform encephalopathy (aka mad cow disease) and scrapie.

[0005] Vegetable products (such as soy and wheat) and monocultures (or
well characterized mixed communities) of single-cell (i.e., microbial)
protein sources have been evaluated as food additives. For example,
microorganisms have been grown on substrates including natural gas (e.g.,
Norferm's currently abandoned Bioprotein® product, for example as
described in U.S. Patent Publ. Nos. 2005/0124053 and 2005/0271771).
Additional organisms that may be incorporated into animal food include
algae, yeast, and zooplankton. An extreme example of alternative animal
food sources is found in some developing-world aquaculture operations
where the feces of pigs, ducks, cows, humans, and other animals have been
utilized as a feed in order to recover the nutritional value remaining in
these waste products. However, the use of such products as a feed may
compromise animal (or human) health or impart an undesirable taste to the
meat of animals fed in this manner.

[0006] Thus, raw material inputs for producing conventional animal foods
draw from various sources, either directly from natural sources or
derived as by-products from the manufacture of other food products. The
incorporation of sufficient protein into the ultimate animal food is a
major manufacturing goal, and greatly influences the total cost of
producing animal feedstocks. Increasingly, food producers, particularly
in the aquaculture and domesticated animal food industries, have utilized
fish meal harvested from various natural fisheries. However, this
dependence has led to concerns about the depletion of natural resources.

[0007] As discussed above, animal foods can be supplemented with
waste-by-products derived from the production of human or animal foods or
ingredients for animal or human foods. The term "human or animal foods"
includes any food or beverage for human or animal consumption, as well
components of human or animal foods (e.g., corn syrup, molasses, etc.).
Food production processes can produce waste streams containing "solid
matter residuals" (i.e., solid waste streams) or "waterborne residuals"
(i.e., dissolved and particulate waste matter entrained in water). When
by-products are used in the production of another salable product (such
as animal feed), the process is commonly referred to as co-production.
For example, fish meal is the product of processed whole food (school
fish such as menhaden, anchovies, sardines, etc.) or food processing
residuals (fish heads, bones, internal organs), while wheat middlings (a
solid matter residual) are a co-product food additive which can be used
as an ingredient in animal food. Further examples of solid matter
residuals used in animal foods include waste hops, barley, and yeast from
breweries (e.g., for cattle, horses, and chickens).

[0008] Waterborne residuals are generally treated in wastewater treatment
plants, where contaminants from the aqueous waste streams (i.e.,
wastewater) are removed prior to the ultimate disposal of the treated
waste water in a receiving water body or another wastewater treatment
plan (e.g., a river or a larger wastewater treatment plant). Waterborne
residuals can also be subjected to pretreatment in which the wastewater
producer partially treats the wastewater to remove at least a portion of
the waterborne residuals prior to sending the wastewater to another
wastewater treatment plant (e.g. a municipal wastewater treatment plant).
Wastewater can derive from industrial processes (such as a food
processing facility, where sewage inputs are not necessarily present) and
domestic sources (such as a municipality, where sewage inputs are primary
contributors to overall flow). The most common contaminants present in
wastewater include soluble, carbon-containing (i.e., organic) compounds
that contribute to biochemical oxygen demand (BOD). BOD is a measure of
the oxygen required for biological degradation of the contaminants in
water or wastewater and is generally correlated to the amount of
waterborne organic material contained in that wastewater. In other words,
the greater the organic matter content of a wastewater, the greater will
be the BOD level determined for that wastewater. In order to meet most
regulatory standards in the United States, BOD levels should generally
fall below about 30 mg/L prior to discharge to a receiving water body.
Influent wastewaters to wastewater treatment plants may vary greatly with
regard to their BOD concentrations and biochemical characteristics. For
example, food-producing facilities may generate wastewaters containing
BOD levels in excess of 30,000 mg/L while wastewater treatment plants
processing municipal sewage generally receive wastewater averaging
between approximately 200 mg/L and 400 mg/L. Furthermore, wastewater may
contain BOD-contributing compounds having a wide range of chemical
structures and molecular weights.

[0009] Many wastewater treatment processes rely upon the biological
conversion of a BOD substrate into a cellular mass. In some
cases--particularly in the food industry--biological treatment processes
may prove difficult to implement as the result of nutrient limitations
(e.g., due to the presence of nitrogen, phosphate, or some other
essential nutritional component in concentrations insufficient to promote
the balanced growth of microbial cells). Balanced growth in bacteria
means that sufficient quantities of nutrients are both present and
biologically available at the time that the organisms in the organic
substrate come into contact. The simultaneous presence of substrate and
nutrients allows bacteria to produce the molecular components most
generally associated with cellular growth, specifically protein, nucleic
acids, and lipids. When sufficient quantities of nutrients (including
both so-called "macronutrients" such as nitrogen and phosphorus, and
so-called "micronutrients" such as metals and vitamins) are not present,
bacteria experience non-balanced growth. In contrast to balanced growth,
non-balanced growth is characterized by the increased production of
polysaccharide material about the cell--a process by which carbon atoms
are sequestered away from the molecules involved with cellular growth
(e.g., proteins, nucleic acids, and lipids).

[0010] FIG. 1 provides a schematic for a typical type of wastewater
treatment plant using a biological treatment process. Influent wastewater
containing food byproducts 1 is introduced to the treatment process (FIG.
1). Although plant designs may vary, the essential biological wastewater
treatment process involves contacting microorganisms (especially
bacteria) with waterborne organic material (i.e., BOD) in the wastewater.
Commonly, this contact occurs in an aeration basin (or series of basins)
4 in which oxygen is introduced to maintain aerobic conditions. The
microorganisms metabolize the waterborne residuals contained in the
wastewater, thereby utilizing available energy (in the form of reduced
carbon compounds) contained therein. In the process of meeting cellular
metabolic needs, including maintenance and growth (i.e., cellular
proliferation), residual matter (i.e., BOD-contributing compounds) in the
wastewater is metabolized and converted into microbial mass. In order to
separate treated water from this solid microbial mass (aka solids), the
contents of the aeration basin(s) 4 can be allowed to settle in a
clarifier basin 5 (it will be understood that other types of separation
equipment could be substituted for a clarifier basin). A portion of the
separated solids (i.e., containing bacteria) 7 is then returned to the
aeration basin(s) 4 to maintain a high concentration of organisms
therein. In order to maintain quasi-steady state conditions, those solids
not returned to the aeration basin must be "wasted" (i.e., removed) 8
from the treatment process. These wasted solids are commonly referred to
as waste activated sludge (WAS). Therefore, as a result of biological
wastewater treatment processes, the aqueous residuals (i.e.,
BOD-contributing compounds) in the influent wastewater stream are largely
incorporated into cellular solids that ultimately must exit the treatment
process while the treated water 6 (with greatly reduced BOD levels) is
discharged to a receiving water body. Removed cellular solids (i.e., WAS)
are collected and disposed of in a variety of ways, most commonly after
partially removing the intracellular water (i.e., dewatering) in a
dewatering process.

[0011] FIG. 2 outlines one conventional process for dewatering and
disposal of this cellular material. Waste solids 15 are applied to a belt
filter press 16 that partially removes the intracellular water contained
therein. This method of dewatering is one of several conventional
methods, which can include centrifugation, drying, various types of
filter presses, etc. Upon introduction to the belt press, the solids
content in WAS is often less than approximately 3% solids on a percent by
weight basis. However, at the completion of belt-press dewatering, the
solids content in the resulting filter-cake (comprised of partially
dewatered biological solids, aka biosolids) 17 is often between about 15%
and about 20% solids. The intracellular water removed during dewatering
(i.e., filtrate) is normally returned to the wastewater treatment process
18. The partially dewatered solids must then undergo a solids disposal
process 19. These disposal options are generally costly to the producer
of the biosolids material, primarily due to the high cost of
transportation and tipping. As a result, biosolids producers often
process the biosolids before and after dewatering to decrease the volume
of material for disposal. Such processes include aerobic and anaerobic
digestion--to convert particulate carbon matter (i.e., solids that would
otherwise require disposal) to gaseous forms such as carbon dioxide and
methane. These volatile components may be either released directly to the
atmosphere or burned, thereby decreasing the amount of solids material
requiring disposal. Other processes for decreasing the quantity of
biosolids requiring dewatering include anaerobic biological treatment
processes in which decreased cellular material is produced from the
energy-containing BOD.

[0012] Other alternatives for disposing of biosolids from wastewater
treatment plants (i.e., WAS) include ocean dumping, incineration,
land-filling, and land-application. However, ocean dumping has become
increasingly more regulated and costly due to concerns about
contaminating the environment. Similar concerns have led many wastewater
treatment plants to move away from WAS incineration due both to
regulatory concerns and to the high energy input required. Land-filling
of WAS is also problematic since most facilities will not accept wet
matter. Likewise, land-application of WAS can engender strong community
resistance and strict regulatory controls due to concerns over pathogenic
organism dispersal (for example, regulatory requirements for composting
processes require careful temperature monitoring to ensure
de-activation--i.e., killing--of the microorganisms comprising the
biosolids).

[0013] Due to these concerns, the composting of biosolids has become a
more attractive method for disposing of waste microorganisms derived from
wastewater treatment processes. As a result of proper implementation of
composting procedures, wastewater treatment plants may even be able to
generate modest incomes by selling compost material (generally referred
to as "Class A biosolids" see 40 C.F.R. §503). Alternatively,
thermally dewatered biosolids have also been sold as fertilizers and soil
conditioners (e.g., Milorganite® fertilizer and soil conditioner, a
product manufactured by the Milwaukee Metropolitan Sewerage District).

[0014] U.S. Pat. No. 4,119,495 describes extracting protein from
hydrolyzed WAS to provide a nutrient source for culturing other
microorganisms, such as yeast, or as a protein additive for feeding
animals. However, this process involves costly pH and temperature
adjustments in order to recover microbial protein. Other researchers have
evaluated using the activated sludge component from domestic wastewater
treatment processes as a foodstuff, but as yet no large-scale commercial
process for so doing has been implemented (Anwar et al., Aquaculture,
vol. 28 (1982) pp. 321-325; Tacon and Ferns, Agriculture and Environment,
vol. 4 (1978/1979) pp. 257-269; Tacon and Ferns, Nutrition Reports
International, vol. 13 (1976) pp. 549-562; Tacon, Proc. World Symp. On
Finfish Nutrition and Fishfeed Technology, Hamburg 20-23 Jun., 1978, Vol.
II. Berlin 1979; Edwards, 1992, Reuse of Human Wastes in Aquaculture: A
Technical Review, UNDP-World Bank Water and Sanitation Program).

BRIEF SUMMARY OF THE INVENTION

[0015] In one embodiment, the present invention is directed to a process
comprising: adding an aqueous waste stream comprising metabolizable
components to a growth vessel containing at least one bacterial culture,
at a first flow rate; allowing the bacteria of the at least one bacterial
culture to grow in the growth vessel by metabolizing at least a portion
of the metabolizable components of the aqueous waste stream, thereby
forming a bacterial suspension in an aqueous bulk liquid, wherein the
aqueous bulk liquid is depleted of metabolizable components relative to
the aqueous waste stream; separating a portion of the bacterial
suspension from the aqueous bulk liquid, thereby forming a bacterial
mass; removing a portion of the bacterial mass at a second flow rate;
returning a portion of the bacterial mass to the growth vessel at a third
flow rate; removing a portion of the aqueous bulk liquid at a fourth flow
rate, wherein the aqueous bulk liquid is substantially free of total
suspended solids; adjusting the second flow rate to provide a MCRT of the
bacteria of no more than about 8 days; and drying the removed bacterial
mass within a time period whereby MWRT-MCRT≦about 2 days.

[0016] In another embodiment, the present invention is directed to a
wastewater treatment unit comprising: a growth vessel; means for adding
an aqueous waste stream comprising metabolizable components to the growth
vessel; at least one bacterial culture in the growth vessel, which
metabolizes at least a portion of the metabolizable components of the
aqueous waste stream, thereby forming a bacterial suspension in an
aqueous bulk liquid, wherein the aqueous bulk liquid is depleted of
metabolizable components relative to the aqueous waste stream; means for
aerating the bacterial suspension and aqueous bulk liquid in the growth
vessel; means for separating a portion of the bacterial suspension from
the aqueous bulk liquid, thereby forming a bacterial mass; means for
removing the bacterial mass from the wastewater treatment unit; means for
adjusting the rate at which the bacterial mass is removed to provide a
MCRT of the bacteria in the wastewater treatment unit of no more than
about 8 days; means for removing a portion of the aqueous bulk liquid
from the wastewater treatment unit, wherein said aqueous bulk liquid is
substantially free of total suspended solids; means for drying the
removed bacterial mass; and means for adjusting the time period in which
the removed bacterial mass is dried whereby MWRT-MCRT≦about 2
days.

[0017] A method comprising: receiving an aqueous waste stream from a food
and/or beverage processing plant comprising dissolved or suspended
metabolizable food and/or beverage byproducts with BOD levels of
≧about 100 mg/L; adding the aqueous waste stream comprising
metabolizable components to a growth vessel containing at least one
bacterial culture, at a first flow rate; allowing the bacteria of the at
least one bacterial culture to grow in the growth vessel by metabolizing
at least a portion of the metabolizable components of the aqueous waste
stream, thereby forming a bacterial suspension in an aqueous bulk liquid,
wherein the aqueous bulk liquid is depleted of metabolizable components
relative to the aqueous waste stream; separating a portion of the
bacterial suspension from the aqueous bulk liquid, thereby forming a
bacterial mass; removing the bacterial mass at a second flow rate;
removing a portion of the aqueous bulk liquid at a third flow rate,
wherein the aqueous bulk liquid is substantially free of total suspended
solids and has a BOD within permitted levels; adjusting the second flow
rate to provide a MCRT of the bacteria of no more than about 8 days;
drying the removed bacterial mass within a time period whereby
MWRT-MCRT≦about 2 days; and providing the dried bacterial mass as
a protein source for animal feed.

[0018] A composition comprising: a bacterial mass comprising a mixture of
bacteria, wherein said bacteria are selected from the group consisting of
genetically modified bacteria, Micrococci, Bacilli, Flavobacteria,
methanogens, Pseudomona, Nitrosomona, Nitrobacteri, Alcaligenes,
nitrifying bacteria, aerobic heterotrophs, and combinations thereof;
wherein said bacterial mass has a protein content of 45% or greater.

[0019] Apparatus and methods for processing an aqueous waste stream are
described herein. In some embodiments, a method includes receiving a
first signal associated with a quantity of a first portion of a bacterial
mass within a waste water treatment system. In some embodiments, the
first signal can be proportional to a flow rate of a waste stream
entering the waste water treatment system. The first portion of the
bacterial mass is contained within a first portion of an aqueous bulk
liquid within the waste water treatment system. A total cell mass of the
bacterial mass within the waste water treatment system is calculated
based on at least the first signal. A second signal associated with a
quantity of a second portion of the bacterial mass is received. The
second portion of the bacterial mass is contained within a second portion
of the aqueous bulk liquid, which is exiting the waste water treatment
system at a flow rate. The method then includes calculating a mean cell
retention time of the bacterial mass within the waste water treatment
system based on the total cell mass of the bacterial mass within the
waste water treatment system and the second signal. The flow rate of the
second portion of the aqueous bulk liquid is adjusted such that the mean
cell retention time of the bacterial mass within the waste water
treatment system is within a predetermined range. The predetermined range
can be, for example, a time period between approximately two days and
approximately eight days.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a schematic of a conventional wastewater treatment plants
using a biological process.

[0021] FIG. 2 is a schematic of a conventional process for dewatering and
disposing of WAS.

[0022] FIG. 3 is a schematic of the process of the present invention.

[0023]FIG. 4 is a schematic illustration of a waste water treatment
according to an embodiment.

[0024] FIG. 5 is a flow chart of a method of adjusting a flow rate of an
aqueous bulk liquid within a waste water treatment system according to an
embodiment.

[0025]FIG. 6 is a flow chart of a method of adjusting a contract price
associated with a waste water treatment process according to an
embodiment.

[0026] FIG. 7 is a flow chart of a method of adjusting a portion of a
waste water treatment process according to an embodiment.

[0027]FIG. 8 is a graphical representation of a cost of treating an
aqueous waste stream and a value of the recovered products as a function
of time according to an embodiment.

[0030] All documents cited are incorporated herein by reference in their
entirety for all purposes; the citation of any document is not to be
construed as an admission that it is prior art with respect to the
present invention.

[0032] The terms "nutrients", metabolizable components",
"carbon-containing compounds" are used interchangeably to refer to
organic compounds that an organism needs to live and grow.

[0033] In one embodiment, the present invention is directed to a process
for preparing a dried bacterial mass suitable for use as a protein
source, e.g. in animal feeds, particularly feeds for animals raised for
human consumption such as in aquaculture.

[0034] More specifically, the present invention is directed to a process
in which wastewater from the waste streams of food or beverage processing
plants is used as a growth medium for single celled organisms (e.g.,
bacteria) which are then harvested as inexpensive cost effective protein
source suitable for use in animal feeds. Wastewater from food or beverage
in processing plants can be characterized by its BOD level, which
generally correlates to the amount of waterborne organic material in the
wastewater. As discussed above, in order to meet wastewater discharge
regulations food and beverage processing plants often rely on biological
conversion of the organic material in the wastewater to reduce the BOD to
within the regulated level. However, the bacterial mass formed and
removed during the biological conversion process (i.e., WAS) is typically
discarded by any of a variety of methods discussed above. Thus, food
processors incur the cost of operating the wastewater treatment process
as well as discarding the WAS. In order to minimize the WAS disposal
costs (which are typically based on the weight or volume of the WAS), the
WAS is typically "digested" (i.e., using endogenous decay to break down
the bacterial mass into volatile compounds). While this reduces the
volume of the solid waste stream, the protein content of the digested WAS
is also degraded.

[0035] As in conventional wastewater treatment processes, the process of
the present invention also provides for the biological treatment of the
organic material present in the wastewater from a food or beverage
processing plant, thereby reducing the BOD of the wastewater to levels
that meet discharge regulations. However, the treatment process of the
present invention differs from that of conventional waste treatment
processes in that it is controlled, as described herein, to maximize the
protein level in the bacterial mass produced in and removed from the
treatment process.

[0036] Furthermore, rather than digesting the bacterial mass, the process
of the present invention provides for drying the bacterial mass almost
immediately after removal in order to preserve and to maximize the
protein content and quality therein. The dried biosolids removed from
conventional waste treatment processes may have ash percentages in excess
of 35%. Since ash comprises refractory material (generally inorganic)
that animals cannot fully metabolize, it is desirable to reduce ash
production by modifying the operating conditions in the wastewater
treatment plant. In conventional wastewater treatment processes, the
production of biosolids is viewed as somewhat of a liability since it
must be disposed of as waste. Even if it is further treated to produce a
commercial product (e.g., compost material) such products are of
relatively low value. Accordingly, WAS is typically digested (i.e.,
stored for days or weeks under either aerobic or anaerobic conditions) in
order to convert some fraction of the solids mass to various gasses and
soluble metabolites, which reduces the organic mass of the WAS. This
enables a conventional treatment facility to reduce the volume of
biosolids requiring disposal, thereby reducing disposal costs. However,
relatively easily digested compounds (such as proteins and lipids) are
metabolized first during digestion, while more refractory molecules and
inorganics remain in the digested WAS. With increasing digestion, the WAS
attains an increasingly high percentage of ash (i.e., refractory or
inorganic matter) at the expense of more valuable, nutritional
components.

[0037] As discussed above, the process of the present invention bypasses
WAS digestion in order to increase the protein and lipid content of the
WAS and to enhance its nutritional value. Bypassing digestion increases
the levels of crude protein in the recovered biosolids by minimizing
degradation. For example, a dried filter-cake biosolids sample from a
conventional wastewater treatment process including a digestion step had
a protein content of approximately 33%, whereas a similar sample removed
prior to digestion (and having a `young` sludge age of approximately 5
days) yielded a protein content of more than 50%--a value approaching the
60% to 70% protein levels generally considered a practical upper limit
for protein levels in bacteria, (Niedhardt et al, Physiology of the
Bacterial Cell: A Molecular Approach, 1990 Sunderland, M A; Gottschalk,
Bacterial Metabolism, 2nd edition, 1986, Springer-Verlag; both of
which are herein incorporated by reference in their entirety for all
purposes).

[0038] In the process of the present invention, the amount of bacterial
mass produced, and the protein levels in the bacterial mass are
controlled by adjusting the mean cell retention time (MCRT) of the
bacterial cells in the process. The MCRT value itself can be controlled
by adjusting the rate at which bacterial mass is removed (also referred
to as "wasted") from the process, as will be described in more detail
below.

[0039] The MCRT can be calculated by dividing the instantaneous total
cellular (e.g., bacterial) mass in the wastewater treatment process by
the bacterial mass removed per unit time. The total bacterial mass in the
process can be measured by various conventional methods, for example by
removing wastewater samples of known volume from the process, measuring
the bacterial mass in those samples, and extrapolating the bacterial mass
in those samples to that of the total bacterial mass in the entire volume
of the wastewater treatment process. Other methods of estimating the
total bacterial mass will be evident to those of ordinary skill in the
art. Thus, if the total bacterial mass is 100 pounds, and 20 pounds of
bacterial mass are removed per day, the MCRT value would be 5 days.

[0040] In one embodiment, the MCRT of the process of the present invention
should be adjusted to no more than about 8 days. In other embodiments the
MCRT is maintained at no more than about 7 days, no more than about 6
days, no more than about 5 days, no more than about 4 days, or no more
than about 3 days, or no more than about 2 days (inclusive of all ranges
and subranges between any of the above stated values). Alternatively
stated, no more than about 1/8, 1/7, 1/6, 1/5, 1/4, 1/3, or 1/2 of the
bacterial mass should be removed from the treatment process per day
(inclusive of all ranges and subranges between any of these values). In
still other embodiments, the MCRT is about 1 to 6 days, about 1 to 4
days, or about 1 to 3 days. If the MCRT is greater than about 6 days,
lower yields of protein are obtained because the average age of the
bacterial cells is too high, and relatively old bacterial cells are
subjected to endogenous decay that results in a lowering of total protein
content, and in some cases, lower quality protein. If the MCRT value is
too low (e.g., lower than about 1 day), the bacterial cells suspended in
the bulk liquid are unable to settle in a gravity settler, and therefore
alternative separation methods such as dissolved air flotation and
membrane bioreactors must be used to separate "young" cells from the bulk
liquid. In general, cells that are 2.5 days or older settle well. If
ammonia must be removed from the wastewater (e.g., as dictated by a
wastewater treatment permit), then the cells cannot be significantly
younger than about 4 days.

[0041] In addition, it has been found that controlling the "mean waste
residence time" (MWRT) in conjunction with the MCRT provides improved
protein levels from the harvested bacterial mass. The MWRT is the mean
residence time of carbon-containing compounds in the process (e.g., the
organic compounds contributing to the BOD of the waste stream), measured
from the time at which these compounds enter the process (e.g., the
aeration vessel) in the wastewater stream, and ending when the carbon is
recovered in the dried bacterial mass (i.e., after the drying step is
complete). The MWRT is calculated by dividing the total mass of carbon in
the process (e.g., carbon entering the process in the wastewater plus the
carbon content of the bacterial cells suspended in the wastewater-minus
any carbon, e.g., CO2, lost by various metabolic processes or carbon
lost by precipitation, etc.) by the total mass of carbon in the dried
bacterial mass recovered per day. The term "dried bacterial mass" refers
to a bacterial mass dried to a moisture content at which the bacterial
mass is sufficiently stable for storage and transport (e.g. less than
about 30% moisture, less than about 20% moisture, less than about 10%
moisture, less than about 5% moisture, less than about 4% moisture, less
than about 3% moisture, less than about 2% moisture, or less than about
1% moisture). Thus, if the total mass of carbon in the process is 100
pounds, and 15 pounds per day of carbon are recovered after drying the
bacterial mass, the MWRT is about 6.7 days. The MWRT correlates with the
length of time between removing the bacterial mass from the process and
subsequently drying the bacterial mass. Thus, MWRT values can be
controlled by how quickly the bacterial mass is dried upon removal from
the process--low MWRT values can be attained by drying the bacterial mass
almost immediately upon separation and removal. Since MWRT is inherently
limited by MCRT, MWRT values can also be controlled by adjusting the
MCRT. For example, if separation and drying require one day and the MCRT
is 4 days, then reducing MWRT by one day can be accomplished by reducing
MCRT by one day (e.g., by increasing the wasting rate while continuing to
dry the separated cells within one day).

[0042] In one embodiment, the MWRT value for the process of the present
invention is more than about 10 days. In other embodiments, the MWRT
value is no more than about 9 days, no more than about 8 days, no more
than about 7 days, no more than about 6 days, no more than about 5 days,
no more than about 4 days, no more than about 3 days, or no more than
about 2 days (inclusive of all ranges and subranges between any of these
values). In a particular embodiment, the MWRT value is 6.5-7 days or
less. In other embodiments, the MWRT value is 2-5 days or less, or about
2-3 days. If the MWRT is ≧about 7 days, the protein yield from the
process is reduced because some degradation of the bacterial cells can
occur prior to recovery and drying of the bacterial mass. In the process
of the present invention, the MWRT and MCRT values can both be controlled
such that the protein content within the bacterial mass is reduced no
more than 50% during the time period between recovering and drying. In
some embodiments, the relative MWRT and MCRT values can be mathematically
expressed as "MWRT-MCRT", such that MWRT-MCRT is ≦about 2 days. In
other embodiments the value of MWRT-MCRT is ≦about 1 day,
≦about 0.5 days, ≦about 0.25 days≦0.2 days,
≦0.15 days, ≦about 0.1 days, or ≦0.05 days,
inclusive of all values and ranges there between. In still other
embodiments, the value of MWRT-MCRT is about 0.05 to about 0.5 days,
about 0.1 to about 0.5 days, about 0.25 to about 2 days, about 0.25 to
about 1 day, about 0.25 to about 0.5 days, about 0.5 to about 2 days, or
about 0.5 to about 1 day.

[0043] In other embodiments of the process of the present invention, the
entire process is carried out under essentially aerobic conditions. The
term "essentially aerobic conditions" includes embodiments of the process
of the present invention employing an equalization tank (i.e., an
influent holding tank or surge tank which allows the process of the
present invention to operate under steady flow conditions regardless of
the instantaneous volume of wastewater generated by the food processing
plant). Although no treatment of the wastewater in the equalization tank
is intended, under some conditions a small amount of anaerobic digestion
can occur in the equalization tank; however the degree of anaerobic
digestion under such conditions is substantially lower than that provided
by unit operations known in the art which are designed to support
anaerobic digestion processes. Anaerobic process steps, operating
conditions, or unit operations have been found to reduce the quality of
the biomass produced in the subsequent aerobic process (i.e., protein
content, etc.) by converting the waste substrate (e.g., the food-derived
growth medium) to reduced forms that do not support protein production in
bacterial cells in quantities sufficient to produce an economic bacterial
SCP. In addition, anaerobic process steps do not provide significant
amounts of (anaerobic) bacterial protein. In other words, the resulting
crude protein content appears to be limited to <60% when anaerobic
pretreatment of the influent is employed. This relative lack of protein
results in material which is only marginally profitable or unprofitable.

[0044] FIG. 3 schematically illustrates one embodiment of the process of
the present invention. Wastewater from a food manufacturing process 20
and containing waterborne residuals 21 flows into a growth vessel 22. The
growth vessel 22 can have any structure suitable for the growth and
proliferation of microorganisms known in the wastewater treatment art,
including one or more conventional anoxic vessels or one or more
conventional aeration basins in which the residuals (i.e., waterborne,
BOD-containing material) are contacted with suspended microorganisms
(e.g., bacteria, commonly present at less than about 1% solids). Although
not preferred, in some embodiments the growth vessel 22 can also include
a conventional anaerobic vessel. During the biological wastewater
treatment, these microorganisms metabolize the waterborne residuals
present in the wastewater stream, and thereby proliferate while reducing
the BOD levels in the wastewater.

[0045] The microorganisms can be separated from the treated wastewater by
a variety of unit processes including, for example, gravity settling (as
described in US 2003/0232107, herein incorporated by reference in its
entirety for all purposes), dissolved air flotation, a membrane
bioreactor, or other processes known in the art. In one embodiment, the
microorganisms are separated by gravity settling (FIG. 3) wherein the
mixed liquor suspended solids from the aeration basin(s) 22 flow into a
clarifier 23. The microorganisms are allowed to settle to the bottom of
the clarifier, while the overflow (i.e., treated water largely free of
total suspended solids) is discharged from the top of the clarifier into
a receiving water body 24. The underflow (containing the bulk of the
microorganisms originally found in the mixed liquor suspended solids,
generally dewatered to between approximately about 0.1% and about 3%
solids) is split into two streams. The first of these streams is returned
to the wastewater treatment process in order to maintain an adequate
concentration of microorganisms in the process. This first stream is
commonly referred to as return activated sludge (RAS). The second of
these streams (commonly referred to as waste activated sludge or WAS) is
optionally dewatered, then dried within a short time period to a
sufficiently low moisture content to prevent further reduction in the
protein content of the WAS. The dried bacterial mass can then be
optionally further processed into a form (e.g., particles, granules,
pellets, etc.) that is convenient for use as animal feed directly, or for
formulation with other ingredients into animal food.

[0046] As indicated above, in most embodiments the wastewater treatment
process (e.g., 22, FIG. 3) is carried out in a growth vessel. Removal of
the microorganisms from the wastewater, for example using a clarifier
process (e.g., 23, FIG. 3) can be carried out in separate clarifier
vessel, or alternatively both processes can be carried out in the same
vessel (e.g., a sequencing batch reactor) by changing operating
conditions, for example, by periodically shutting down agitation in the
growth vessel, thereby allowing gravity settling and removal of the
microorganisms.

[0047] Other unit processes for separating and recovering the bacterial
cells from the bulk liquid (for example as discussed above) can be used
in place of a clarifier. For example, when the clarifier is replaced with
a dissolved air flotation unit, the overflow of the dissolved air
filtration unit would be split into the return activated sludge (which is
returned to the growth vessel) and waste activated sludge streams, and
the treated wastewater (i.e., treated water largely free of total
suspended solids) would be discharged from the underflow. Another example
includes the use of membrane bioreactors, or MBRs, that employ membrane
filters to separate the bacterial cells from the bulk liquid, oftentimes
within the growth vessel. A portion of these cells could then be returned
to the growth vessel in part or in its entirety, or it could be wasted in
part or in its entirety. Similarly, other unit processes that could be
used for separating and recovering the bacterial cells from the bulk
liquid would be integrated in the appropriate manner with the growth
vessel to provide for growing and proliferating the bacterial mass using
the waterborne residuals contained in the wastewater stream, then
separating and drying the WAS. Regardless of the specific separation
process used, the rate at which WAS is removed from the overall process,
or the rate at which the dried bacterial mass is obtained, wasting and
drying processes are both adjusted so as to provide MCRT, MWRT, and
MWRT-MCRT values as described above. Accordingly, the BOD levels in the
wastewater stream are reduced to sufficiently low levels so as to comply
with permitted levels for discharge into receiving water bodies (e.g.,
lakes, rivers, oceans) while a dried bacterial mass with high protein
levels suitable for use in animal feed is generated economically.

[0048] Prior to being added to the growth vessel, the wastewater and
waterborne residuals therein used in the process of the present invention
are maintained under hygienic conditions like those of the food-quality
materials that comprise conventional food products, so that the ultimate
dried cellular mass obtained from the process of the present invention is
suitable for use in animal feeds for animals raised for human
consumption. For example, in order to maintain the appropriate hygienic
levels of the waste stream, an industrial food processor utilizing the
process of the present invention would avoid disposing of heavy organics
(i.e., degreasers and cleaners), toxic chemicals (including metals), or
sewage into the same wastewater stream, and would treat the waste stream
with at least the same level of care as other by-product streams destined
for animal consumption. In one embodiment, the wastewater and waterborne
residuals comply with the requirements outlined in the American
Association of Feed Control Officials Official Publication (2007) (herein
incorporated by reference in its entirety for all purposes).

[0049] Immediately after separation and removal from the process (e.g.,
from the clarifier, air flotation unit, or membrane bioreactor), but
prior to drying, the solids content of the WAS is typically about 0.1% to
about 3%. Although the WAS can be dried directly, it is often more
efficient and less costly to dewater the WAS prior to drying. In one
embodiment, a belt filter press can be used to provide efficient, partial
dewatering of the WAS. Alternatively, a centrifuge or other means (such
as a vacuum-assisted press, a filter press column, a screw press, a
rotary press, a drum thickener, a gravity belt thickener, electrically
mediated dewatering, extrusion dewatering, a plate and frame press, etc.)
also can be used. The dewatering can also be facilitated by the addition
of flocculating agents, e.g., GRAS (Generally Recognized as Safe)
flocculating agents such as cationic polymers, nonionic polymers, anionic
polymers, acrylamides, polyacrylamides, polyacrylates,
acrylamide-acrylate copolymers, etc. Following dewatering with e.g. a
belt press, the solids content of the WAS increases generally to between
about 4% and about 40%. As a practical matter, it is difficult to remove
all (i.e., 100%) of the water present in the bacterial mass, so terms
such as "wet" and "dry" are relative terms. As discussed above, the term
"dry" refers to a low enough level of water such that the bacterial mass
is sufficiently stable for storage and transport. The term "sufficiently
stable" means that less than about a 5% reduction in protein content is
observed over a 30 day period when stored under normal conditions (e.g.,
a temperature of less than or equal to about 25° C., relative
humidity below about 60%). The solids content of "dry" WAS ranges from
about 80% to about 100%, for example about 80%, about 82%, about 85%,
about 87%, about 90%, about 92%, about 95%, about 97%, about 99%, or
about 100% inclusive of all values, ranges, and subranges therebetween.

[0050] In some embodiments, rather than recovering the biomass in the form
of generally intact microbial cells, at least a portion of the microbial
cells may be lysed by any conventional method, for example to improve
protein digestibility.

[0051] Next, the dewatered WAS can be converted into a form suitable for
an actual animal feed (e.g., a pellet). This unit process includes both
the drying of the bacterial mass and the deactivation of the
microorganisms present therein. For example, after belt pressing, the
dewatered WAS can be subjected to an extrusion process. In the extrusion
process, the dewatered WAS (containing approximately 15% solids) is
pressurized and passed through orifices in order to produce multiple
elongated strands, each with a uniform cross-section (which provides for
even drying and distribution of heat). The strands are then dried
further, typically by maintaining a temperature of 105° C. for a
period of about one day or less. In other embodiments (independently of
the conversion method used), the dewatered WAS can be dried within a
temperature range of 55°-105° C., 65°-95° C.,
or about 80° C., for a time sufficient to reduce the moisture
content to a range of about 10%. For example, the dewatered WAS can be
dried for a time period of less than about a day at a temperature of
about 70°-105° C., dried for a time period of less than
about a day at a temperature of about 70°-95° C., or dried
for a time period of less than about a day at a temperature of about
80° C. In particular embodiments, the dewatered WAS is dried at
about 68° C.±10° C. In other particular embodiments, the
dewatered WAS is dried at about 68° C.±10° C. until a
solids content of at least about 95% is achieved.

[0052] In some embodiments, some portion of the biomass may be retained in
the relatively "clean" water discharged (e.g., from the clarifier, air
flotation unit, or membrane bioreactor) after isolating the WAS from the
process, and may be recovered therefrom using suitable methods. Such
additional recovery steps increase the overall efficiency and cost
effectiveness of the process of the present invention by increasing the
cellular yield from the process and by allowing treatment facilities to
meet effluent requirements. The additional biomass recovered in this
manner may be combined with WAS isolated from e.g., a clarifier, or may
by separately dewatered, dried, and combined with dried biomass obtained
elsewhere in the process.

[0053] Any suitable drying method can be used, provided that the dewatered
WAS is heated at a sufficient time and temperature to dry the bacterial
mass sufficiently without degrading the protein content therein. Drying
methods include, for example single-pass and dual-pass ovens, spray
dryers, rotary drum dryers, tray dryers, solar drying, etc.

[0054] As a result of the drying process, the microorganisms present in
the dried material are "deactivated" or "inactivated". "Deactivation" of
microorganisms is the process by which viable microorganisms are rendered
non-viable with respect to further proliferation (e.g., by killing the
microorganisms). It will be understood that it is generally not practical
to deactivate 100% of all microorganisms present in a microbial cell
mass. Therefore, an "inactivated" microbial cell mass is one in which the
level of inactivation is sufficient to produce a safe food material for
the animals intended to utilize this material as a food. After drying,
the dried bacterial mass has a ratio of protein/ash of about 2.5/1 to
6.5/1 (or about 45% protein/17% ash to about 65% protein/10% ash). In
other embodiments, the protein/ash ratio is about 3.2/1 to 8.1/1 (or
about 55% protein/17% ash to about 65% protein/8% ash). In still other
embodiments, the protein/ash ratio is about 10/1 to 12.5/1 or about 10/1
to about 12.5 to 1. In further embodiments, the ratio of protein to ash
is about 2.7/1, about 2.9/1, about 3.0/1, about 3.4/1, about 3.6/1, about
3.8/1, about 4.0/1, about 4.2/1, about 4.4/1, about 4.6/1, about 4.8/1,
about 5.0/1, about 5.2/1, about 5.4/1, about 5.6/1, about 5.8/1, about
6.0/1, about 6.2/1, about 6.4/1, about 6.6/1, about 6.8/1, about 7.0/1,
about 7.2/1, about 7.4/1, about 7.6/1, about 7.8/1, about 8.0/1, about
8.2/1, about 8.4/1, about 8.6/1, about 8.8/1, about 9.0/1, about 9.2/1,
about 9.4/1, about 9.6/1, about 9.8/1, about 10.0/1, about 10.2/1, about
10.4/1, about 10.6/1, about 10.8/1, about 11.0/1, about 11.2/1, about
11.4/1, about 11.6/1, about 11.8/1, about 12.0/1, about 12.2/1, about
12.4/1, or about 12.5/1, inclusive of all ratios of protein/ash, ranges
of protein/ash, and subranges of protein/ash therebetween.

[0055] The dried and deactivated bacterial mass can then be further
processed, if needed, into a form more suitable for feeding to animals.
For example, dried strands (or alternatively dried sheets or granules) of
the bacterial mass can be chopped, ground, or crushed to provide a
desired pellet size corresponding to the animal for which the food is
intended. For example, fish and cattle generally prefer pellets of
approximately 1/4-inch diameter while chickens generally prefer a coarse
scratch material. A subsequent screening step to remove fines can also be
included when such fines are considered problematic (e.g., in
aquaculture, fines can undesirably compromise water quality). At this
stage, the dried and processed bacterial mass is suitable for use
directly as an animal feed, or can be combined with other ingredients in
the formulation of animal feeds.

[0056] As discussed above, the bacterial biomass produced by any of the
processes of the present invention is different from the biomass WAS
produced from conventional wastewater treatment processes in various
ways. For example, because the wastewater itself is maintained under
hygienic conditions, the resulting biomass does not contain toxic or
otherwise deleterious components (e.g., heavy metals, detergent residues,
etc.) which would render it unsuitable or unfit for consumption by
animals (e.g., fish) which would subsequently be used as food sources for
humans.

[0057] Also, by controlling the process to provide MCRT, MWRT, and
MWRT-MCRT values as described herein, the bacterial biomass produced by
any of the processes of the present invention is of generally higher
quality compared to the protein of biomass produced from wastewater
streams by conventional processes. For example, the levels of free
nucleic acids present in biomass reflect the degree of degradation of the
cells--higher levels of free nucleic acids indicate higher levels of
cellular degradation, and lower quality protein. The level of free
nucleic acids in the biomass produced by the claimed process is generally
about 10% or less (in some embodiments about 9% or less, about 8% or
less, about 7% or less, about 6% or less, about 5% or less, about 4% or
less, about 3% or less, about 2% or less, about 1% or less, inclusive of
values and ranges therebetween). By contrast, conventional processes for
the biological treatment of wastewater streams generally produce biomass
with higher free nucleic acid levels, e.g., about 11-12% or higher. In
addition, the crude protein content (i.e., protein levels estimated based
on the analyzed nitrogen content) of the biomass provided by the process
of the present invention is typically higher than about 56% (for example
about 58%, about 60%, about 62%, about 64%, about 66%, about 68%, about
70%, about 72%, about 74%, about 76%, about 78%, about 80%, about 82%, or
about 84%, inclusive of all values and ranges therebetween), whereas
biomass produced from conventional wastewater treatment processes has a
much lower crude protein content, generally about 30-56%. In one
embodiment, the crude protein values of the biomass produced by the
process of the present invention ranges from about 60-82%. In another
embodiment, the crude protein content ranges from about 66-80%.

[0058] As indicated above, "crude protein" estimates the total protein
content based on the analyzed nitrogen content of the biomass. However,
crude protein values generally overestimate the actual amount of protein
in the biomass, since the analyzed nitrogen content includes nitrogen
from non-proteinaceous sources (nucleic acids, etc.). "True protein"
content is an alternative measure of protein content based on the amount
of amino acids present in the biomass. The processes of the present
invention produce dried biomass having true protein contents higher than
50% (for example, about 51%, about 52%, about 53%, about 54%, about 55%,
about 56%, about 57%, about 58%, about 59%, about 60%, or about 62%,
inclusive of all values and ranges therebetween). In contrast, the
biomass produced from conventional processes generally have true protein
values of <40%.

[0059] The biomass produced by the process of the present invention also
has relatively high levels of vitamin B-12, for example levels greater
than about 5 mg/kg, greater than about 7 mg/kg, greater than about 10
mg/kg, or greater than about 12 mg/kg, inclusive of all values, ranges,
and subranges therebetween.

[0060] Furthermore, and as described herein, the biomass produced by the
various processes of the present invention is typically carried out using
a mixture of different types of microorganisms, typically aerobic
organisms (or facultative aerobes, microaerophiles, etc.), but can also
include anaerobic microorganisms. Using a mixture of different types of
microorganisms can be advantageous in that the population of
microorganisms can adapt to changes in process conditions, whereas
processes using a single type of microorganism (e.g., anaerobes) are more
vulnerable to process "upsets" which could reduce the amount of biomass
produced.

[0061] In addition, the process of the present invention differs from
other known processes for producing animal feeds comprising
microorganism-derived biomass (e.g., Norferm's currently abandoned
process for producing the Bioprotein® product) in that the nutrient
source of the process of the present invention is renewable and much less
expensive--i.e., uses essentially "free" nutrients, which would typically
be discarded, obtained from the wastewater streams of food and beverage
processing plants--whereas e.g. Norferm's process uses relatively
valuable "fossil" hydrocarbons (e.g., natural gas), which would typically
be used as a fuel source, as the nutrient source for methanotrophic
microorganisms. As a result, the process of the present invention is
substantially less expensive and essentially "carbon-neutral"--i.e.,
utilizes a nutrient source comprising biologically derived carbon, rather
than a nutrient source comprising "fossil" carbon (which would increase
the net CO2 levels in the environment).

[0062] The economic advantages of the process of the present invention
result from the fact that wastewater treatment and disposal is generally
considered to be part of the expense of operating a food or beverage
processing plant. Since the process of the present invention produces
biomass suitable for use as animal feed and "treated" wastewater having
low BOD levels suitable for disposal in a receiving body of water, the
process of the present invention effectively does not add additional
wastewater treatment costs, while also producing a commercially valuable
product (i.e. animal feed). Thus, the nutrient source (i.e. wastewater)
for growing the bacterial cells is effectively "free". As a result, the
process of the present invention can provide biomass suitable for use in
animal feeds, as well as the resulting animal feed, at substantially
lower cost than conventional methods.

[0063] Furthermore, since the nutrient source of the microorganisms used
in the process of the present invention is renewable, the biomass
produced from the process is chemically different and can be
distinguished from the biomass derived from non-renewable (i.e., "fossil"
hydrocarbon or petrochemical) sources. As discussed above, the renewable
nutrients used in the various processes of the present invention are
derived from the waste products of processing foods and/or beverages.
These waste products are thus derived from plant or animal sources.
Plants "fix" atmospheric CO2 to product the carbohydrates (i.e.,
sugars, cellulose, etc.) needed by the plant to grow and reproduce, and
animals eat these plants (or eat animals which eat plants). Thus, the
carbon atoms of all animals and plants ultimately derive from atmospheric
CO2.

[0064] Atmospheric CO2 comprises a small amount of the radioactive
isotope 14C. This 14C is produced continuously in the
atmosphere when atmospheric nitrogen atoms are struck by neutrons
produced in the atmosphere by cosmic rays, causing these nitrogen atoms
to lose a proton and form 14C, which is then immediately oxidized to
14CO2. A small but measurable fraction of atmospheric CO2
is thus present in the form of 14CO2. Plants which "fix"
atmospheric CO2, including 14CO2, and the animals which
consume these plants, thus incorporate 14C. 14C decays slowly
to 14N (half-life of 5730 years), and thus "fossil" carbon sources
(e.g., petroleum, natural gas) contain reduced levels of 14C
compared to renewable carbon sources derived from more recent biological
activity. As a consequence, biomass produced from renewable nutrient
sources (i.e., the biomass produced by the various processes of the
present invention) has higher levels of 14C compared to biomass
produced from nutrients comprising "fossil" carbon.

[0065] The 14C content of products can be quantified by various
methods, for example by ASTM test method D 6866-05 ("Determining the
Biobased Content of Natural Range Materials Using Radiocarbon and Isotope
Ratio Mass Spectrometry Analysis", which is incorporated herein by
reference in its entirety). This test method measures the
14C/12C isotope ratio in a sample and compares it to the
14C/12C isotope ratio in a standard 100% biobased material to
give the percent biobased content of the sample. "Bio-based materials"
are organic materials in which the carbon comes from recently (on a human
time scale) fixated CO2 present in the atmosphere. For example, a
bio-based material typically has a 14C/12C isotope ratio of
approximately the steady state environmental levels of about 1 ppt (part
per trillion), or slightly lower (i.e., due to a small amount of
radioactive decay). Contrarily, a fossil-based material, has a
significantly lower 14C/12C isotope ratio compared to bio-based
materials, because the initial 14C levels are substantially reduced
by radioactive decay. This ratio can also be reported as a percentage
with the units "pMC" (percent modern carbon). If the material being
analyzed is a mixture of present day radiocarbon and fossil carbon
(containing very low levels of 14C), then the pMC value obtained
correlates directly to the amount of biomass material present in the
sample. The compositions of the present invention have pMC values of at
least about 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75,
80, 85, 90, 95, 100, inclusive of all values and subranges therebetween.
In one embodiment, the compositions of the present invention have a pMC
value is about 100. In other embodiments, the compositions of the present
invention have a pMC of at least about 90.

[0066] The dewatering, drying, and deactivation processes must occur
within a short timeframe following removal of the bacterial mass from the
wastewater treatment process (i.e., to provide MWRT values within the
ranges described above). This short timeframe ensures that the resulting
dried bacterial mass has sufficiently high protein content and quality
suitable for use as animal feed, or animal feed additive. This generally
requires that the dewatering, drying and deactivation processes must
occur in the immediate proximity of the wastewater treatment process
where the bacterial mass is produced.

[0067] The process of the present invention can be operated in a
continuous manner. For example, the wastewater can be introduced into the
growth vessel (e.g., aeration basin) continuously, and the WAS and the
total suspended solids-free treated wastewater can be removed
continuously. In addition, the WAS removed from the process can be
optionally dewatered and then dried continuously as well. Alternatively,
the process of the present invention can be operated in a batch mode,
wherein the flow of wastewater can be interrupted, and the WAS removed
from the process can be stored for a period of time or transported to
another location, e.g. within the process tanks, or in a holding vessel,
or via trucks, pipelines, etc., before drying. In other embodiments, the
wastewater and treated wastewater largely free of total suspended solids
can be introduced and removed, respectively, on a continuous basis, while
a batch of the WAS removed in the process is stored briefly before being
dried.

[0068] In a particular embodiment, the process of the present invention is
operated in a continuous manner under consistent conditions year-round in
order to maximize protein content and minimize variability, as variation
in e.g. protein content of more than about ±5-10% can cause
difficulties in formulating animal feeds from the compositions of the
present invention.

[0069] Microorganisms suitable for use in the process of the present
invention include genetically modified bacteria, Pseudomonas,
Flavobacteria, Achromobacteria, Micrococci, Bacilli, Alcaligenes,
methanogens, Nitrosomonas, Nitrobacteria, nitrifying bacteria (e.g.,
bacteria which convert NH3 to NO3.sup.-), aerobic heterotrophs
(e.g., obligate or facultative aerobes that use an organic substrate for
growth and development), any of the microorganisms described in U.S. Pat.
No. 4,317,843 (which is herein incorporated by reference in its entirety
for all purposes) and combinations thereof.

[0070] The growth vessel can contain a single strain of bacteria (e.g., a
single strain of any of the bacteria described herein), or two or more
strains of bacteria (e.g., a combination of any of the bacteria described
herein). In one embodiment, the bacteria or mixture of bacteria are
selected to provide a dried bacterial mass having a crude protein content
of about 45% or more. In other embodiments, the crude protein content of
the dried bacterial mass is about 50% or more, about 55% or more, about
60% or more, about 65% or more, about 70% or more, or about 75% or more
(inclusive of all values or subranges therebetween). In certain
embodiments, the crude protein content of the dried bacterial mass can be
less than about 45%, for example about 30-45%.

[0071] In other embodiments, the amino acid levels, total amino acid
levels, and crude protein levels are at least those of the following
table:

[0073] In a particular embodiment, genetically modified bacteria are
employed. Suitable genetically modified bacteria include bacteria
modified to express in excess of 65% protein, or higher levels of lysine
(e.g., approximately 5.5% of the total material), methionine (e.g.,
approximately 2.3% of the total material), cysteine (e.g., approximately
0.6% of the total material), histidine (e.g., approximately 2% of the
total material), and arginine (e.g., approximately 4.4% of the total
material).

[0074] In the process of the present invention, bacteria can be added to
the growth vessel either as a seed (i.e., prior to start-up of the waste
treatment process) or as a supplement to the bacteria population already
present. The conventional practice for wastewater treatment plant
start-up involves transporting solids from an existing treatment plant.
These solids may have been in contact with municipal sewage. However, in
the process of the present invention it is desirable to avoid contacting
microorganisms destined for animal feed with municipal sewage. However,
microorganisms derived from (i.e., the "offspring" of) bacterial
populations present in sewage plants can be used, provided that the
process itself is not contaminated by components of the sewage which
would render the ultimate biomass produced unsuitable for use in animal
feeds. Accordingly, in one embodiment of the process of the present
invention, any of the various bacteria appearing on the list of food
additives approved for direct feeding to humans compiled by the United
States Food and Drug Administration (Association of American Feed Control
Officials, 2001 Official Publication, herein incorporated by reference in
its entirety for all purposes) can be used to produce a suitable
bacterial culture containing one or more types of bacteria. For example,
one or more strains of the "approved" bacteria indicated above are loaded
into a fermentor (e.g. a chemostat, a sequencing batch reactor, etc.).
The final concentration of bacteria in the mixed liquor suspended solids
of the fermentor should fall between approximately 1000 mg/L and 10,000
mg/L, or another concentration (e.g., about 1500 mg/L, about 2000 mg/L,
about 2500 mg/L, about 3000 mg/L, about 3500 mg/L, about 4000 mg/L, about
4500 mg/L, about 5000 mg/L, about 5500 mg/L, about 6000 mg/L, about 6500
mg/L, about 7000 mg/L, about 7500 mg/L, about 8000 mg/L, about 8500 mg/L,
about 9000 mg/L, or about 9500 mg/L, inclusive of all values, ranges, and
subranges there between) that provides ready settling of the bacterial
flocs or otherwise facilitates recovery of the bacterial mass (e.g., by
air flotation, using a membrane bioreactor, etc.). The fermentor can be
of conventional designs that include means for mixing the culture of
microorganisms, introducing substrate-containing water, maintaining
appropriate redox conditions, and decanting water following the settling
of bacterial flocs. The substrate-containing influent to the fermentor is
actual process-water, containing waterborne BOD-contributing residuals
from a food processing operation. The decanted water from the fermentor
is mostly depleted of this BOD, having provided energy and substrate to
meet the growth and maintenance needs of the bacterial culture. During
the growth of the bacterial culture, parameters such as total suspended
solids, volatile suspended solids, fixed suspended solids, and sludge
volume index are determined as a means of monitoring growth and settling
properties of the bacterial culture. At various stages in the development
of the bacterial culture, bacterial growth requires moving the bacteria
from a fermentor of a given size to an incrementally larger apparatus to
accommodate the increasing number of microorganisms. This task must
always provide for maintaining an appropriate sludge volume index in the
mixed liquor suspended solids of a fully charged reactor, generally
between about 100 L/kg and about 300 L/kg. The ultimate goal of this
culturing procedure is to create a controlled community of innocuous
microorganisms that constitute the activated sludge component of an
industrial-scale process-water treatment plant. The waste activated
sludge from this plant, in either liquid or filter-cake form can be
utilized to inoculate future treatment plants using this community of
microorganisms. Alternatively, specific bacteria or enzymes could be
introduced into the process on a continuous basis in a manner that
enhances the production of protein and other nutritional components.

[0075] The bacterial culture in the process of the present invention can
comprise mixtures of different bacterial strains, or can comprise a
bacterial monoculture. For example, the bacterial culture in the process
of the present invention can be a monoculture derived from pharmaceutical
production processes (using fermentative processes). As a result of the
tight controls employed in the production of pharmaceutical products, the
filter-cake provided by such operations comprises homogeneous bacterial
populations (generally monocultures) of single-cell organisms. Such well
characterized bacterial cultures can be used in the process of the
present invention to produce microbial food products consisting of a
controlled community (or even a single species) of microorganism(s)
rather than spontaneous or amended populations of mixed bacteria.

[0077] In order to maximize the proliferation of bacteria in the process
of the present invention, nutrients can be added to the wastewater in the
growth vessel. Suitable nutrients include, for example, macronutrients,
micronutrients, vitamins, amino acids, and combinations thereof. These
nutrients should be added in sufficient amounts to provide for balanced
growth of the bacterial culture as described above.

[0078] A non-limiting list of suitable macronutrients include any
biologically assimilable source of C, H, O, N, and P, for example sugars,
phosphates, and ammonia.

[0079] A non-limiting list of suitable micronutrients includes
biologically acceptable sources of K, Mg, Ca, Na, Fe, S, B, Zn, I, Cu,
Co, Mo, Mn, Se, Ni, Al, Ag, Cr, F, Si, Sn, V, Ba, and combinations
thereof. It will be understood that "biologically acceptable" refers to a
source of the indicated element, in the appropriate form suitable for
absorption and utilization by microorganisms. In some cases, the
"suitable" form will be elemental, but in other cases, the micronutrient
will be in the form of a salt or a compound containing the element. Thus,
for example, a biologically acceptable source of K and Na includes salts
of K.sup.+ and Na.sup.+ such as KCl, K.sup.+ acetate, NaCl, Na.sup.+
acetate, etc.; biologically acceptable sources of Mg and Ca include salts
of Mg2+ and Ca2+ such as MgSO4, CaSO4, etc.;
biologically acceptable sources of Fe include salts of Fe3+ such as
Fe2(SO4)3; biologically acceptable sources of S and Se
include S or Se containing amino acids such as cysteine and
selenocysteine; biologically acceptable sources of Zn include Zn2+
salts such as Zn2+ acetate, Zn2+ sulfate, and Zn2+
gluconate; biologically acceptable sources of I include I.sup.- salts
such as NaI; biologically acceptable sources of Cu include Cu2+
salts such as CuSO4; biologically acceptable sources of Ni include
Ni2+ salts such as NiCl2 and its hydrates; biologically
acceptable sources of Co include vitamin B12; biologically
acceptable sources of Mo include molybdate salts such as
Na2MoO4; biologically acceptable sources of Mn include MnO,
Mn2O, or MnSO4; biologically acceptable sources of F include
F.sup.- salts such as NaF and SnF2; biologically acceptable sources
of V include V2+ salts such as VSO4; biologically acceptable
sources of B include B3+ salts including boric acid; and
biologically acceptable sources of Ba include Ba2+ salts such as
BaCO3.

[0083] Ultimately, the dried bacterial mass provided by the process of the
present invention is fed to animals by conventional methods (e.g.,
spreaders, troughs, etc.). The term "feeding" or "fed" to animals means
the oral ingestion and subsequent internal metabolism of a food material
by animals. The animal food comprising the dried bacterial mass produced
by the process of the present invention meets the daily metabolic needs
of the animals, including growth and maintenance, thereby providing
animals suitable for human or animal consumption. Food comprising the
dried bacterial mass provided by the process of the present invention can
be fed to various animals, including mammals, birds, and fish. In one
embodiment, the fish include those of the biological class Osteichthyes,
such as but not limited to any of the following: tilapia, milkfish, bass,
sturgeon, catfish, salmon, tuna, perch, bluegill, bream, walleye, trout,
cobia, and carp. In another embodiment, the mammals include sheep,
cattle, horses, swine, mink and other furbearing animals, and goats. In
yet another embodiment, the birds include poultry such as turkeys,
chickens, ducks, and geese.

[0084] If the dried bacterial mass is deficient in specific nutrients
(e.g., vitamins, minerals, carbohydrates, lipids, or fiber), they may be
added to the dried bacterial mass during the formulation of the animal
food or, as an alternative, separately supplied to the animals without
being mixed into the biosolids. Similarly, in order to customize the
composition of the ultimate food product to the target animal, other
`bulking` materials (e.g., wheat middlings, potato shavings, etc.) can be
added to the biosolids to improve the structural properties or
digestibility of the animal food. Other additives such as colorants or
flavoring agents (e.g., dyes, fish oil, or herbal extracts) can also be
added to the animal food comprising dried bacterial mass produced in the
process of the present invention as a means of improving the commercial
quality of the meat obtained from the animals. In addition, the biosolids
produced by the process of the present invention can also be mixed with
other animal feeds to produce the ultimate animal feed. In other words,
the biosolids produced by the process of the present invention can be
amended with other components in much the same manner as, for example,
fish meal is used today. Animal feed formulations comprising the dried
bacterial mass produced by the process of the present invention can be
formulated using conventional methods, for example using Brill
Formulation Software, to provide well-characterized formulated animal
feeds.

[0085] The present invention is also directed to a wastewater treatment
unit for treating wastewater from a food and/or beverage processing
plant. The wastewater treatment plant of the present invention comprises
a growth vessel; means for adding an aqueous waste stream comprising
metabolizable components to the growth vessel; at least one bacterial
culture in the growth vessel, which metabolizes at least a portion of the
metabolizable components of the aqueous waste stream, thereby forming a
bacterial suspension in an aqueous bulk liquid, wherein the aqueous bulk
liquid is depleted of metabolizable components relative to the aqueous
waste stream; means for aerating the bacterial suspension and aqueous
bulk liquid in the growth vessel; means for separating a portion of the
bacterial suspension from the aqueous bulk liquid, thereby forming a
bacterial mass; means for removing the bacterial mass from the wastewater
treatment unit; means for adjusting the rate at which the bacterial mass
is removed to provide a MCRT of the bacteria in the wastewater treatment
unit of no more than about 8 days; means for removing a portion of the
aqueous bulk liquid from the wastewater treatment unit, wherein said
aqueous bulk liquid is substantially free of total suspended solids;
means for drying the removed bacterial mass; and means for adjusting the
time period in which the removed bacterial mass is dried whereby
MWRT-MCRT≦about 2 days.

[0086] As described above, the growth vessel can include e.g. a membrane
bioreactor, fermentation vessel, or one or more aeration tanks.

[0088]FIG. 4 is a schematic illustration of a waste water treatment
system 100 according to an embodiment. The waste water treatment system
100 includes a vessel 120, a first (e.g., variable-speed) pump 130, a
second (e.g., variable-speed) pump 132, a third (e.g., variable-speed)
pump 134 and a controller 110. The vessel 120, which can be any vessel of
the types shown and described herein, includes a growth portion 122 and a
clarifying portion 123. The growth portion 122 is configured to contain
bacteria and/or promote bacterial growth as described herein. The
clarifying portion 123 is configured to promote separation of a bacterial
mass from an aqueous bulk liquid, as described herein. Although the
growth portion 122 and the clarifying portion 123 are shown schematically
as being included in a single structure (i.e., the vessel 120), in other
embodiments, the growth portion 122 and the clarifying portion 123 can be
included in separate and/or distinct structures. Similarly stated, in
other embodiments, the waste water treatment system 100 can include any
number of vessels in which any of the various operations described herein
can take place. Moreover, although the growth portion 122 and the
clarifying portion 123 are shown schematically as being spatially
distinct portions of the vessel 120, in other embodiments, the growth
portion 122 and the clarifying portion 123 can occupy the same region of
the vessel 120. In some embodiments, for example, the vessel 120 can be a
sequencing batch reactor.

[0089] As described above, an aqueous waste stream can be conveyed into
the vessel 120 via the first flow passageway 140, as shown by the arrow
AA in FIG. 4. The aqueous waste stream can be any waste stream of the
types shown and described herein. For example, in some embodiments, the
aqueous waste stream can be generated by a food processing plant, and can
include a metabolizable component, such as, for example, spent grains.
The first pump 130 is disposed within the first flow passageway 140 and
can control the flow rate Q1 of the aqueous waste stream into the vessel
120. Similarly stated, the first pump 130 can adjust the flow rate Q1 of
the aqueous waste stream into the vessel 120.

[0090] After the aqueous waste stream enters the vessel 120, at least a
portion of the metabolizable components within the aqueous waste stream
are metabolized to form a bacterial mass suspended within an aqueous bulk
liquid within the vessel 120. A first portion of the suspended bacterial
mass is identified as BM1 in FIG. 4. As described herein, the bacterial
mass can be separated from the aqueous bulk liquid in the clarifying
portion 123 of the vessel 120. Similarly stated, within the clarifying
portion 123 of the vessel 120 the aqueous bulk liquid can be separated
into a discharge portion DIS that is substantially free of suspended
solids and a second portion of the bacterial mass BM2 that contains the
bacterial mass produced within the vessel 120.

[0091] The second portion of bacterial mass BM2 of the aqueous bulk liquid
can be conveyed out of the vessel 120 via a second flow passageway 142,
as shown by the arrow BB in FIG. 4. As described herein, after the second
portion of bacterial mass BM2 exits the vessel 120, the second portion of
bacterial mass BM2 can be further processed into a form convenient for
use as animal feed. Such additional processing can include, for example,
dewatering, drying or the like. The second pump 132 is disposed within
the second flow passageway 142 and can control the flow rate Q2 of the
second portion of bacterial mass BM2 of the aqueous bulk liquid within
the second flow passageway 142. As described in more detail herein, the
second pump 132 can adjust the flow rate Q2 of the second portion of
bacterial mass BM2 out of the vessel 120.

[0092] The discharge portion DIS of the aqueous bulk liquid can be
conveyed out of the vessel 120 via a third flow passageway 144, as shown
by the arrow CC in FIG. 4. As described herein, the discharge portion DIS
can be conveyed into a receiving body of water. The third pump 134 is
disposed within the third flow passageway 144 and can control the flow
rate Q3 of the discharge portion DIS of the aqueous bulk liquid within
the third flow passageway 144. As described in more detail herein, the
third pump 134 can adjust the flow rate Q3 of the discharge portion DIS
out of the vessel 120.

[0093] The controller 110 is configured to automatically adjust the flow
rate Q1 of the aqueous waste stream into the vessel 120, the flow rate Q2
of the bacterial mass portion BM2 of the aqueous bulk liquid out of the
vessel 120 and/or the flow rate Q3 of the discharge portion DIS of the
aqueous bulk liquid out of the vessel 120. In this manner, the controller
110 can maintain the properties of the second portion of bacterial mass
BM2 and/or the discharge portion DIS. For example, in some embodiments,
the controller 110 can adjust the flow rate Q2 of the second portion of
bacterial mass BM2 of the aqueous bulk liquid out of the vessel 120 such
that the MCRT of the bacterial mass within the waste water treatment
system 100 is within a predetermined range. The predetermined range of
the MCRT can be any of the ranges disclosed herein, such as, for example
a range between approximately 2 days and approximately 8 days.

[0094] The controller 110 includes a processor 112 that is operatively
coupled to a first sensor 114, a second sensor 116 and a third sensor
118. The processor 112 is also operatively coupled to the first pump 130,
the second pump 132 and the third pump 134. The first sensor 114 is
configured to produce a signal S1 associated with a quantity of the first
portion BM1 of the bacterial mass within the waste water treatment system
100. The first sensor 114 can be any suitable sensor for measuring the
quantity of the first portion BM1 of the bacterial mass within a sampled
portion of the aqueous bulk liquid in the waste water treatment system
100. For example, in some embodiments, the first sensor 114 can measure
the concentration of the first portion of the bacterial mass BM1 within
the sampled portion of the aqueous bulk liquid. In some embodiments, the
first sensor 114 can produce the first signal S1 as a function of, for
example, the conductivity of the sampled portion of the aqueous bulk
liquid, the acidity of the sampled portion of the aqueous bulk liquid
and/or the optical properties (e.g., light transmission properties) of
the sampled portion of the aqueous bulk liquid. Other methods of
obtaining a signal based on the quantity of the first portion BM1 of the
bacterial mass (e.g., gravimetric, etc.) can also be used.

[0095] The processor 112 is configured to receive the signal S1 and
calculate a total cell mass of the bacterial mass within the waste water
treatment system 100. As described above, in some embodiments, the
processor 112 can be configured to calculate a total cell mass by
extrapolating based on the quantity of the first portion BM1 of the
bacterial mass. In other embodiments, the processor 112 can maintain a
temporal log of the quantity of the first portion BM1 of the bacterial
mass such that calculation of the total cell mass accounts for temporal
fluctuations in the contents of the aqueous waste stream entering the
vessel 120.

[0096] Although the first sensor 114 is shown as being included within the
vessel 120, in other embodiments, the first sensor 114 can be disposed in
any suitable location within the waste water treatment system 100. For
example, in some embodiments, first sensor 114 can be disposed within the
first passageway 140 and can thus measure the concentration of the
bacterial mass within the aqueous waste stream entering the vessel 120.
In such embodiments, the first sensor 114 can also produce a signal
associated with the flow rate Q1 of the aqueous waste stream entering the
vessel 120. In this manner, the first sensor 114 can produce the signal
S1 associated with the bacterial mass entering the vessel 120.

[0097] Although the controller 110 is shown as including a single first
sensor 114, in other embodiments, the controller 110 can include any
number of sensors configured to produce signals associated with a
quantity of various portions of the bacterial mass within the waste water
treatment system 100. Similarly stated, in some embodiments, the
controller 110 can include multiple sensors, each configured to produce a
signal associated with a quantity of bacterial mass within a particular
location of the waste water treatment system 100. In this manner, the
processor 112 can calculate the total cell mass of the bacterial mass
within the waste water treatment system 100 based on received input from
various sensors. Thus, in such embodiments, the calculation of the total
cell mass can account for spatial variability in the contents of the
waste water treatment system 100.

[0098] The second sensor 116 is configured to produce a signal S2
associated with a quantity of the second portion BM2 of the bacterial
mass exiting the waste water treatment system 100. Similarly stated, the
second sensor 116 is configured to produce a signal S2 associated with a
quantity of the second portion BM2 of the bacterial mass as the second
portion BM2 flows within the second passageway 142. The second sensor 116
can be any suitable sensor for measuring the quantity of the second
portion BM2 of the bacterial mass within a sampled portion of the aqueous
bulk liquid in the waste water treatment system 100, such as the sensor
types described above with reference to the first sensor 114. For
example, in some embodiments, second sensor 116 can produce a signal
associated with the flow rate Q2 of the aqueous bulk liquid exiting the
vessel 120.

[0099] The processor 112 is configured to receive the signal S2 and
calculate the mean cell retention time (MCRT) of the bacterial mass
within the waste water treatment system 100. As described above, the MCRT
can be calculated as a function of the total cell mass of the bacterial
mass within the waste water treatment system 100 and the quantity of the
second portion BM2 of the bacterial mass exiting the waste water
treatment system 100. In some embodiments, the processor 112 can
calculate the MCRT for a predetermined period of time (e.g., for a period
of one hour). In this manner, the processor 112 can track the temporal
fluctuation in the MCRT. In other embodiments, the processor 112 can
calculate the MCRT substantially in real time.

[0100] In some embodiments, the processor 112 is configured to receive the
signal S2 and calculate the mean waste residence time (MWRT) of the
bacterial mass within the waste water treatment system 100. As described
above, the MWRT can be calculated as a function of the MCRT and the time
period within which the additional processing of the second portion BM2
of the bacterial mass is completed. Such additional processing can
include, for example, dewatering, drying or the like.

[0101] The third sensor 118 is configured to produce a signal S3
associated with a quantity of the bacterial mass exiting the waste water
treatment system 100 within the discharge portion DIS of the aqueous bulk
liquid. Similarly stated, the third sensor 118 is configured to produce a
signal S3 associated with a BOD of the discharge portion DIS of the
aqueous bulk liquid. The third sensor 118 can be any suitable sensor for
measuring the quantity of the bacterial mass within a sampled portion of
the aqueous bulk liquid in the waste water treatment system 100, such as
the sensor types described above with reference to the first sensor 114.

[0102] The processor 112 is configured to produce a first control signal
S1' received by the first valve 130, a second control signal S2' received
by the second valve 132 and a third control signal S3' received by the
third valve 134. In this manner, the controller 110 can maintain the
properties of the second portion of bacterial mass BM2 and/or the
discharge portion DIS by controlling the flow of the aqueous waste stream
into the vessel 120, by controlling the flow of the second portion BM2 of
the bacterial mass out of the vessel 120 and/or by controlling the flow
of the discharge portion DIS of the aqueous bulk liquid out of the vessel
120. In some embodiments, for example, the processor 112 can
automatically adjust (i.e., adjust without substantial human
intervention) the flow rate of the aqueous waste stream into the vessel
120. In some embodiments, for example, when the MCRT of the bacterial
mass within the waste water treatment system 100 begins to decrease, the
first control signal S1' can be adjusted such that the first pump 130
allows a higher flow rate of the aqueous waste stream into the vessel
120, thereby increasing the total cell mass of the bacterial mass within
the waste water treatment system 100. In other embodiments, the first
control signal S1' can be adjusted to reduce the flow rate of the aqueous
waste stream into the vessel 120 when the MCRT of the bacterial mass
within the waste water treatment system 100 begins to increase. In this
manner, the MCRT and/or the MWRT of the bacterial mass can be
automatically maintained within a predetermined range.

[0103] In some embodiments, the processor 112 can automatically adjust
(i.e., adjust without substantial human intervention) the flow rate of
the second portion BM2 of the bacterial mass out of the vessel 120. In
some embodiments, for example, when the MCRT of the bacterial mass within
the waste water treatment system 100 begins to decrease, the second
control signal S2' can be adjusted such that the second pump 132 reduces
the flow rate of the second portion BM2 of the bacterial mass out of the
vessel 120, thereby increasing the MCRT. In other embodiments, the second
control signal S2' can be adjusted to allow an increased flow rate of the
second portion BM2 of the bacterial mass out of the vessel 120 when the
MCRT of the bacterial mass begins to increase beyond a predetermined
control point.

[0104] In some embodiments, the processor 112 can automatically adjust
(i.e., adjust without substantial human intervention) the flow rate of
the discharge portion DIS of the aqueous bulk liquid out of the vessel
120. In some embodiments, for example, when the BOD of the discharge
portion DIS is above a predetermined threshold, the third control signal
S3' can be adjusted such that the third pump 134 reduces the flow rate of
the discharge portion DIS of the aqueous bulk liquid out of the vessel
120. In this manner, the controller 110 can maintain the BOD of the
discharge portion DIS within predetermined limits.

[0105] The processor 5950 can include a memory device (not shown)
configured to receive and store information, such as a series of
instructions, processor-readable code, a digitized signal, or the like.
The memory device can include one or more types of memory. For example,
the memory device can include a read only memory (ROM) component and a
random access memory (RAM) component. The memory device can also include
other types of memory suitable for storing data in a form retrievable by
the processor 5950, for example, electronically-programmable read only
memory (EPROM), erasable electronically-programmable read only memory
(EEPROM), or flash memory.

[0106] The pumps 130, 132, 134 can be any suitable pump for producing
and/or controlling the flow rates Q1, Q2 and Q3 shown above. For example,
in some embodiments, any of the pumps 130, 132, 134 can be a variable
speed, positive displacement pump (e.g., a gear pump, a vane pump, a
piston pump or the like). In other embodiments, any of the pumps 130,
132, 134 can be a non-positive displacement pump (e.g., an impeller pump)
configured to operate at either a constant speed or at variable speeds.
In yet other devices, the waste water system 100 need not include pumps,
but can rather include any suitable device configured produce and/or
control the flow rates Q1, Q2 and/or Q3 shown above. For example, in some
embodiments, the waste water treatment system 100 can include one or more
valves configured to control the flow rates Q1, Q2 and/or Q3 shown above.

[0107] Although the waste water treatment 100 is shown and described as
including a pump 134 configured to produce and/or control flow rate Q3 of
the discharge portion DIS of the aqueous bulk liquid out of the vessel
120, in other embodiments, the flow rate Q3 of the discharge portion DIS
can be produced and/or controlled by gravity. In such embodiments, for
example, the third flow passageway 144 can be devoid of any pump and/or
valve. In such embodiments, the flow rate Q3 of the discharge portion DIS
can be controlled indirectly by controlling the flow rate Q1 and/or the
flow rate Q2, as described herein.

[0108] Although second flow passageway 142 is shown as being configured to
convey substantially all of the second portion of bacterial mass BM2 out
of vessel 120, in other embodiments, a portion of the second portion of
bacterial mass BM2 can be returned to the vessel 120 by a return
passageway (not shown in FIG. 4). In this manner, a desired concentration
of biologically active organisms can be maintained in the vessel 120. In
such embodiments, the return passageway can include a sensor and a pump
similar to the sensors and pumps described above.

[0109] The processor 112 can be any processing device configured to
receive, store and process information, as described herein, such as a
series of instructions, processor-readable code, a digitized signal, or
the like. In some embodiments, the processor 112 can be a
commercially-available processing device (or set of devices) configured
to receive the signals and perform the calculations described herein. The
processor 112 can include programmable control settings to adjust the
control signals S1', S2' and/or S3' as a function of the error between a
target setting and an actual value. Such control settings can include,
for example, proportional, integral and/or derivative gain settings. In
this manner, for example, the processor 112 can adjust the control
signals S1', S2' and/or S3' in a manner that maintains control of the
MCRT of the bacterial mass without causing significant temporal
fluctuations in the MCRT.

[0110] In some embodiments, the processor 112 can include a memory device
(not shown) configured to receive and store information. The memory
device can include one or more types of memory. For example, the memory
device can include a read only memory (ROM) component and a random access
memory (RAM) component. The memory device can also include other types of
memory suitable for storing data in a form retrievable by the processor
112, for example, electronically-programmable read only memory (EPROM),
erasable electronically-programmable read only memory (EEPROM), or flash
memory.

[0111] Although the sensors 114, 116 and 118 are shown and described above
as being disposed within a portion of the vessel 120 and/or the flow
passageways, in other embodiments, a sensor can be disposed in any
location suitable for monitoring the waste treatment process. For
example, in some embodiments, the waste water treatment system 100 can
include one or more sensors disposed apart from the aqueous bulk liquid.
For example, in some embodiments, the waste water treatment system 100
can include a sensor configured to produce a signal associated with a
characteristic of the second portion of bacterial mass BM2 as it
undergoes the additional processing (e.g., the dewatering, drying or the
like). In some embodiments, a sensor can be configured to produce a
signal associated with a water content of the second portion of the
bacterial mass BM2 after it undergoes a drying process. In other
embodiments, a sensor can be configured to produce a signal associated
with a protein content of the second portion of the bacterial mass BM2.
Such a sensor can be, for example, a sensor configured to analyze various
constituents (e.g., Nitrogen) of an exhaust gas produced by combusting a
sample of the second portion of the bacterial mass. In this manner, the
controller 110 can receive any suitable signal and can adjust the flow
rates Q1, Q2 and/or Q3 and/or any other process parameter based on the
received signal such that the biological mass (e.g., BM2) produced by the
waste water treatment system 100 has desired properties (e.g., water
content, protein level or the like). Thus, the waste water treatment
system 100 can reduce variability that can be associated with external
factors, such as, for example, change of seasons, change in content of
incoming waste stream, degradation of organisms within vessel 120, change
in performance of components of water treatment system, or the like.

[0112] Moreover, although the sensors 114, 116 and 118 are shown
schematically as being integrated devices configured to measure a
property and output a signal in response to the measurement, in some
embodiments, a sensor can include multiple different devices that
cooperatively produce a signal associated with a characteristic of the
bacterial mass. For example, a sensor can include a sample volume, a
dryer and a scale configured measure a resulting mass. The signal can be
associated with the measurement produced by the scale. Moreover, the
signal can be conveyed to the processor 112 in any suitable fashion, such
as, for example, electronically (via a wireless or wired connection),
manually (e.g., via input from a keyboard), or the like.

[0113] FIG. 5 is a flow chart of a method 200 of adjusting a flow rate of
a liquid within a waste water treatment system according to an
embodiment. The waste water treatment system can be any of the systems
shown and described herein, such as, for example, the waste water
treatment system 100 shown and described with reference to FIG. 4. The
method includes receiving a first signal that is associated with a
quantity of a first portion of a bacterial mass within a waste water
treatment system, at 202. The first portion of the bacterial mass, which
can be, for example, the first portion BM1 shown in FIG. 4, is contained
within a first portion of an aqueous bulk liquid within the waste water
treatment system. The first signal can be any signal of the types shown
and described above, and can include for example, information associated
with a flow rate of an aqueous waste stream into the waste water
treatment system.

[0114] A total cell mass of the bacterial mass within the waste water
treatment system is calculated based on at least the first signal, at
204. As described above, the total cell mass can be extrapolated from the
information contained within the first signal. In other embodiments, the
total cell mass can be calculated based on the information contained
within the first signal over a predetermined time period.

[0115] A second signal associated with a quantity of a second portion of
the bacterial mass is received, at 206. The second portion of the
bacterial mass, which can be, for example, the second portion BM2 shown
in FIG. 4, is contained within a second portion of the aqueous bulk
liquid exiting the waste water treatment system at a flow rate. The
method then includes calculating an MCRT of the bacterial mass within the
waste water treatment system based on the total cell mass of the
bacterial mass and the second signal, at 208.

[0116] The flow rate of the second portion of the aqueous bulk liquid is
adjusted such that the MCRT of the bacterial mass within the waste water
treatment system is within a predetermined range, at 210. In some
embodiments, the flow rate of the second portion of the aqueous bulk
liquid exiting the system can be adjusted automatically via a controller,
such as, for example, the controller 110 shown and described above. In
some embodiments, for example, the flow rate of the second portion of the
aqueous bulk liquid exiting the system can be controlled substantially in
real time to maintain the MCRT within the predetermined range (e.g.,
between approximately two days and approximately eight days). In some
embodiments, the method can optionally include adjusting the flow rate of
the second portion of the aqueous bulk liquid such that the MWRT of the
bacterial mass within the waste water treatment system is within a
predetermined range, at 212.

[0117] The one or more bacterial cultures in the growth vessel can include
any of those described herein, and combinations thereof.

[0118] The means for aerating the bacterial suspension and aqueous bulk
liquid in the growth vessel can include air diffusers or membrane
diffusers in the shape of the disc, tube, or plate which is used to
transfer air into the wastewater. Diffusers can use either rubber
membranes or ceramic elements typically and produce either fine or coarse
bubbles. These are referred to as fine bubble diffusers or coarse bubble
diffusers. They are typically connected to a piping system which is
supplied with pressurized air by a blower. Other examples of means for
aerating include mechanical aerators (low or high speed mixers,
submersible and surface aerators), jet aerators (Venturi), and paddle
aerators.

[0119] Means for separating the bacterial suspension from the aqueous bulk
liquid can include any of those disclosed herein.

[0120] Means for removing the bacterial mass from the wastewater treatment
unit include pumps and the associated piping or open channels or weirs
connected to the separator unit.

[0121] The means for adjusting the rate at which the bacterial mass is
removed includes flow controllers which control variable-speed pumps (or
alternatively, the opening and closing of valves) attached to the
separator unit, thereby adjusting the flow rate at which the WAS is
removed from the separator unit. The flow controller can be a
computerized controller connected to the valves controlling the rate of
introduction of the wastewater, the valves controlling the rate of
removal of WAS, and valves controlling the rate of removal of the total
suspended solids-free treated wastewater. The computerized controller can
monitor the relative flow rates and solids concentrations and thereby
adjust the rate at which WAS is removed relative to the rate at which
wastewater is introduced in order to provide an MCRT value as described
herein.

[0122] The means for removing a portion of the aqueous bulk liquid from
the wastewater treatment unit including pumps and the associated piping,
open channels, weirs, etc. connected to the separation unit.

[0123] The means for drying the removed bacterial mass includes any of the
types of ovens described herein, or solar drying.

[0124] The means for adjusting the time period at which the removed
bacterial mass is dried include controllers which adjust the rate at
which the bacterial mass is produced into a drying unit (e.g., oven). If
the bacterial mass (e.g., WAS) is dewatered prior to drying, the means
for dewatering include any of those described herein, including a belt
filter press, a centrifuge, a vacuum assisted press, a plate filter
press, a screw press, a rotary press, a drum thickener, a gravity belt
thickener, and electrically mediated the watering unit, and extrusion the
watering unit, and a plate and frame press.

[0125] The means for adding nutrients to the growth vessel include storage
tanks, flow monitoring equipment, dosing pumps, and the associated
piping, open channels, weirs, etc. connected to the influent stream
and/or the wastewater treatment vessels.

[0126] As discussed above, wastewater from food processing plants can be
treated using the process of the present invention to provide an effluent
wastewater stream with BOD levels in compliance with permitted levels,
allowing for discharge into receiving water bodies or to a sewer
connected to a treatment facility permitted to discharge to a receiving
water body. In addition, relatively high amounts of biosolids (compared
to conventional wastewater treatment processes) are recovered, which have
a protein content and quality suitable for use as an ingredient in animal
feeds, e.g. for aquaculture. Thus, the cost of treating the wastewater
and disposing of the resulting biosolids can be offset by the economic
value of the ingredient.

[0127] Accordingly, the wastewater treatment process of the present
invention can be used as part of a business method comprising:
identifying a food processing company that generates an aqueous waste
stream comprising dissolved or suspended metabolizable food and/or
beverage by-products with BOD levels of ≧about 100 mg/L (for
example BOD levels ranging from about 200,000 mg/L to about 200 mg/L, for
example about 100,000 mg/L, about 50,000 mg/L, about 30,000 mg/L, about
20,000 mg/L, about 10,000 mg/L, about 1,000 mg/L, about 800 mg/L, about
400 mg/L, or about 200 mg/L), wherein the food processing company incurs
treatment costs to reduce the BOD levels of the aqueous waste stream to
within permitted levels; decreasing the treatment costs to the food
processing company for reducing the BOD of the aqueous waste stream by a
process comprising: adding an aqueous waste stream comprising
metabolizable components to a growth vessel containing at least one
bacterial culture, at a first flow rate; allowing the bacteria of the at
least one bacterial culture to grow in the growth vessel by metabolizing
at least a portion of the metabolizable components of the aqueous waste
stream, thereby forming a bacterial suspension in an aqueous bulk liquid,
wherein the aqueous bulk liquid is depleted of metabolizable components
relative to the aqueous waste stream; separating a portion of the
bacterial suspension from the aqueous bulk liquid, thereby forming a
bacterial mass; removing the bacterial mass at a second flow rate;
removing a portion of the aqueous bulk liquid at a third flow rate,
wherein the aqueous bulk liquid is substantially free of total suspended
solids and has a BOD within permitted levels; adjusting the second flow
rate to provide a MCRT of the bacteria of no more than about 8 days; and
drying the removed bacterial mass within a time period whereby
MWRT-MCRT≦about 2 days; selling the dried bacterial mass as a
protein source.

[0128] In one embodiment, a revenue stream can be generated by contracting
with the food processing company to set up and operate a wastewater
treatment process according to the present invention at a reduced cost to
the food processing company (relative to the waste treatment and disposal
costs of a conventional wastewater treatment process). That is, the food
processing company pays the operator of the wastewater treatment process
processing fees which are lower than the operating cost of a conventional
wastewater treatment process. In this manner, the food processing company
reduces wastewater treatment costs, and the operator of the wastewater
treatment process of the present invention obtains two revenue
streams--treatment fees and profits from selling the high protein content
biosolids as in animal feed or animal feed supplement. Alternatively, in
another embodiment, the food processing company would provide the
wastewater free of charge to the operator of the wastewater treatment
plant, who would then derive a revenue stream from sale of the biosolids
produced in the treatment process. In some embodiments the "food
processing company" and "operator" can be the same entity--i.e., the food
processing company can operate the process of the present invention.

[0129] In other embodiments, the wastewater stream or usage rights thereto
could be purchased at a cost such that the value of biosolids derived
from the process exceed the purchase cost plus operating costs of the
wastewater treatment process, etc.

[0130]FIG. 6 is a flow chart of a method 300 of adjusting a contract
price associated with a waste water treatment process according to an
embodiment. The illustrated method includes calculating a processing cost
associated with reducing a BOD level of an aqueous waste stream from an
input BOD level to an output BOD level, at 302. For example, as described
herein, the processing cost can include the cost associated with reducing
the BOD level of an aqueous waste stream from a food-processing plant
(e.g., a brewery) from a value greater than 100 mg/L to a value below 100
mg/L. The processing cost can be calculated based on any factor that
contributes to the cost of treating the incoming waste water stream. Such
factors can include, for example, a volume cost associated with a flow
rate of waste water treated, an energy cost associated with pumping
and/or transferring materials in the water treatment system, a residence
time cost associated with the length of time that portions of the waste
water stream reside within the water treatment system, an energy cost
associated additional processing (e.g., dewatering, drying or the like)
of a bacterial mass produced during the treatment, an overhead cost
associated with the operation of the system, and/or a capital cost
associated with capital projects for the system. In some embodiments, for
example, the processing cost can be calculated based on the MCRT of the
bacterial mass within the treatment system. For example, in some
embodiments, the processing cost can increase proportionally to the MCRT.
In other embodiments, the processing cost can be calculated based on the
MWRT of the bacterial mass, thereby including factors such as the drying
time into the processing cost. For example, in some embodiments, the
processing cost can increase proportionally to the MWRT.

[0131] The processing cost can be calculated in any suitable manner. For
example, in some embodiments, the processing cost can be calculated
substantially in real time. For example, in some embodiments, the
processing cost can be calculated based on receiving one or more signals
from a sensor measuring the treatment operation, such as, for example,
the sensors 114, 116 and 118 shown and described above. In this manner,
the processing cost can be calculated automatically as a function of time
and/or for a predetermined time period. Thus, in some embodiments, the
processing cost can be calculated as an average of multiple processing
costs, each associated with a predetermined time period. For example, in
some embodiments, the method can include calculating a daily, weekly
and/or monthly processing cost.

[0132] In some embodiments, the processing cost can be calculated by a
system configured to control and/or monitor the waste water treatment
process. For example, in some embodiments, the processing cost can be
calculated by a controller similar to the controller 110 shown and
described above. In this manner, the calculation of the processing cost
and the controlling of the waste water treatment process can be performed
by a common system (e.g., the controller 110). Thus, in some embodiments,
as described below, the common system can adjust a portion of the waste
water treatment process based on at least the calculated processing cost.
For example, in some embodiments, the controller (e.g., controller 110)
can calculate the processing cost and adjust a portion of the waste water
treatment process to maintain the processing cost within a predetermined
limit.

[0133] A recovery value associated with a bacterial mass removed from the
aqueous waste stream when the BOD level of an aqueous waste stream is
reduced from the input BOD level to the output BOD level is calculated,
at 304. For example, as described herein, the recovery value that can be
any value realized in connection with the bacterial mass resulting from
the treatment of the aqueous waste stream, such as, for example, the sale
of the bacterial mass for animal feed. The recovery value can be
calculated based on any factor such as a protein content of the bacterial
mass (e.g., the crude protein content or the true protein content), the
ash content of the bacterial mass, the cost of shipping the bacterial
mass and/or market conditions. Market conditions can include, for
example, the daily market price for certain animals and/or livestock, the
market price for animal feed components (e.g., corn, soybean, etc.) or
the like.

[0134] In some embodiments, the recovery value can be calculated
substantially in real time. For example, in some embodiments, the
recovery value can be calculated based on receiving one or more signals
from a sensor measuring the treatment operation, such as, for example,
the sensors 114, 116 and 118 shown and described above. In this manner,
the recovery value can be calculated automatically as a function of time
and/or for a predetermined time period. Thus, in some embodiments, the
recovery value can be calculated as an average of multiple recovery
values, each associated with a predetermined time period. For example, in
some embodiments, the method can include calculating a daily, weekly
and/or monthly recovery value.

[0135] In some embodiments, calculating the recovery value can include
receiving a signal associated with a protein content of the bacterial
mass. The signal can be produced by a sensor configured to measure and/or
estimate the protein content of a bacterial mass. In some embodiments,
for example, the recovery cost per unit weight of the bacterial mass
increases proportionally to the protein content of the bacterial mass. In
other embodiments, the recovery value can be calculated based on the MCRT
and/or the MWRT, which, as described above, can be an indicator of the
protein content of the bacterial mass.

[0136] In some embodiments, the recovery value can be calculated by a
system configured to control and/or monitor the waste water treatment
process. For example, in some embodiments, the recovery value can be
calculated by a controller similar to the controller 110 shown and
described above. In this manner, the calculation of the recovery value
and the controlling of the waste water treatment process can be performed
by a common system (e.g., the controller 110). Thus, in some embodiments,
as described below, the common system can adjust a portion of the waste
water treatment process based on at least the calculated recovery value.
For example, in some embodiments, the controller (e.g., controller 110)
can calculate the recovery value and adjust a portion of the waste water
treatment process to maintain the recovery value within a predetermined
limit.

[0137] The illustrated method includes adjusting automatically a contract
price associated with reducing the BOD level of the aqueous waste stream
based on at least the processing cost and the recovery value, at 306. The
contract price is the price that the producer of the aqueous waste stream
pays to have the BOD level of an aqueous waste stream reduced from the
input BOD level to the output BOD level. In some embodiments, the
contract price can be proportional to a difference between the recovery
value and the processing cost. As described above, in some embodiments,
the contract price can be calculated and/or updated as a function of time
and/or for a predetermined time period. Thus, in some embodiments, the
contract price can be calculated as an average of multiple contract
prices, each associated with a predetermined time period. For example, in
some embodiments, the method can include calculating a daily, weekly
and/or monthly contract price. In this manner, the contract price can be
automatically adjusted periodically based on changing conditions.

[0138] In some embodiments, the contract price can be adjusted by a system
configured to control and/or monitor the waste water treatment process.
For example, in some embodiments, the contract price can be adjusted by a
controller similar to the controller 110 shown and described above. In
this manner, the adjustment of the contract price and the controlling of
the waste water treatment process can be performed by a common system
(e.g., the controller 110). Thus, in some embodiments, as described
below, the common system can adjust a portion of the waste water
treatment process based on at least the contract price. For example, in
some embodiments, the controller (e.g., controller 110) can adjust and/or
calculate the contract price and adjust a portion of the waste water
treatment process to maintain the contract price within a predetermined
limit.

[0139] In some embodiments, the method optionally includes generating an
invoice reflecting the adjusted contract price, at 308. The invoice can
be either a hard-copy invoice (e.g., that is mailed to the producer of
the waste stream) or a paperless invoice (e.g., that is transmitted
electronically to the producer of the waste stream).

[0140] Although the method 300 shown and described above is associated
with adjusting a contract price based on changing conditions, in other
embodiments a method can include adjusting the waste treatment process
based on a processing cost and/or a recovery value. In this manner, the
waste treatment process can be adjusted to ensure that the waste stream
is treated in a cost-effective manner. Said another way, in this manner,
the characteristics (e.g., protein level, water content or the like) of
the bacterial mass resulting from the waste water treatment process can
be changed based on a processing cost and/or a recovery value. For
example, FIG. 7 is a flow chart of a method 400 of adjusting a waste
water treatment process according to an embodiment. The method 400 is
described with reference to FIG. 8, which illustrates a graphical
representation 450 of an embodiment having processing cost and a recovery
value that vary as a function of certain parameters of the waste
treatment process. In particular, the vertical axis, labeled as
"cost/value," corresponds to the cost and/or value associated with a
portion of a the waste treatment process. The horizontal axis, labeled as
"time," corresponds to the time period associated with a portion of the
waste treatment process. The time period can be, for example, the MCRT
and/or the MWRT. Although the horizontal axis corresponds to a time
period associated with a portion of the waste treatment process, in other
embodiments, the horizontal axis can correspond to any parameter, the
variance of which can result in a change in the cost and/or value
associated with a portion of the waste treatment process.

[0141] A solid line represents a recovery value curve 452, which is the
recovery value for the bacterial mass removed during the waste water
treatment process as a function of the MWRT. A first dashed line
represents a first processing cost curve 454, which is the cost of
processing the waste stream as a function of the MWRT. A second dashed
line represents a second processing cost curve 456, which is the cost of
processing the waste stream as a function of the MWRT.

[0142] Referring to FIG. 7, the illustrated method includes calculating a
processing cost associated with a process of reducing a BOD level of an
aqueous waste stream from an input BOD level to an output BOD level, at
402. The processing cost can be calculated in any suitable manner and by
any suitable device, such as those described above with reference to the
method 300. Moreover, as shown in FIG. 8, the processing cost can be
calculated as a function of the MWRT. As shown, the processing cost
curves 454, 456 increase with increasing MWRT. Such an increase can be
attributed to many factors, including, but not limited to, the energy
cost associated with drying the bacterial mass resulting from the waste
treatment process. In other embodiments, the processing cost can be
calculated as a function of the MCRT and/or any other parameter
associated with the waste treatment process.

[0143] Referring to FIG. 7, the illustrated method includes calculating
recovery value associated with a bacterial mass removed during the waste
treatment process, at 404. The recovery value can be calculated in any
suitable manner and by any suitable device, such as those described above
with reference to the method 300. Moreover, as shown in FIG. 8, the
recovery can be calculated as a function of the MWRT. As shown, the
recovery value curve 452 initially increases with increasing MWRT, but
then decreases beyond a threshold value of the MWRT. In some embodiments,
the variance of the recovery value curve 452 can be attributed to the
change in the protein content of the recovered bacterial mass as a
function of MWRT. In other embodiments, the recovery value can be
calculated as a function of the MCRT and/or any other parameter
associated with the waste treatment process.

[0144] Referring to FIG. 8, the cross-hatched region 460 between the
recovery value curve 452 and the first processing cost curve 454
graphically shows the range of MWRT within which the recovery value is
greater than the processing cost. Similarly stated, the cross-hatched
region 460 between the recovery value curve 452 and the first processing
cost curve 454 graphically shows the range of MWRT within which the waste
treatment process is profitable. Moreover, the cross-hatched region 460
includes a target value T1 of the MWRT at which the difference between
the recovery value and the processing cost is maximized. Similarly
stated, the target value T1 of the MWRT is the MWRT at which the
profitability of the waste treatment process is maximized. In some
embodiments, the target value T1 can be, for example, 6.5 days.

[0145] Under certain conditions, the processing cost and/or the recovery
value as a function of the MWRT can change. Such change can be due to
changing energy costs, changing material transportation costs or the
like. Thus, under certain conditions, the value of the MWRT at which the
maximum profitability of the waste treatment process occurs can change.
In the example illustrated in FIG. 8, the variability in the processing
cost is represented by the second processing cost curve 456, which
reflects a higher processing cost than the first processing cost curve
454. The cross-hatched region 462 between the recovery value curve 452
and the second processing cost curve 456 graphically shows the range of
MWRT within which the recovery value is greater than the processing cost.
Moreover, the cross-hatched region 462 includes a target value T2 of the
MWRT at which the difference between the recovery value and the
processing cost is maximized. Similarly stated, the target value T2 of
the MWRT is the MWRT at which the profitability of the waste treatment
process is maximized. Referring to FIG. 7, the method includes adjusting
automatically a portion of the process based on at least the processing
cost and the recovery value, at 406. In this manner, the portion of the
process (e.g., the target MWRT) can be adjusted automatically to maximize
the profitability of the waste treatment process.

[0146] In some embodiments, the MWRT can be adjusted by a controller such
as, for example, the controller 110 shown and described above. In some
embodiments, for example, the controller can calculate and updated target
MWRT and can transmit a pump control signal to a valve disposed within
the waste treatment system to change a flow rate within the waste
treatment system, as described above with reference to the method 200.
Although FIG. 8 shows only the processing cost curve as changing, in
other embodiments, the recovery value curve can change due to changing
conditions. In yet other embodiments, both the processing cost curve and
the recovery value curve can change.

[0147] While various embodiments of the invention have been described
above, it should be understood that they have been presented by way of
example only, and not limitation. Where methods described above indicate
certain events occurring in certain order, the ordering of certain events
may be modified. Additionally, certain of the events may be performed
concurrently in a parallel process when possible, as well as performed
sequentially as described above.

[0148] For example, although the method 200 is shown and described as
including calculating a total cell mass before the second signal is
received, in other embodiments, the total cell mass can be calculated
after the second signal is received. In yet other embodiments, the total
cell mass can be calculated as a function of the second signal.

EXAMPLES

Example 1

[0149] Potato-processing and brewery byproducts were evaluated as models
for food processing wastewater streams to produce biosolids. During a
scientifically rigorous feeding trial, bacteria containing 40% protein
were added to ground feed formulations at 0% (control Diet #1), 21.5%
(Diet 2), and 43% (Diet #3) on a mass basis and extruded into pellets.
(As a result, the bacterial cells contributed 0%, 8.4% and 16.8% of the
total protein in final feeds.) Tilapia fingerlings (300 Oreochromis
niloticus fry) were then grouped into "blocks" that consisted of small,
medium, and large fish and were fed one of the three feeds. The growth
results show that the fish receiving the bacterial protein grew at a
faster rate than those receiving conventional ingredients alone (FIG. 9).
At the completion of the experiment, the fish were euthanized and
whole-body analyses were performed for Kjeldahl nitrogen (as a protein
measurement), ash, and total fat. The averages of these analytical
results and the 95% confidence intervals are shown in Table 1 and FIG. 10
and show that fish receiving 43% bacterial cell derived protein (aka
single cell protein, or SCP) possessed the highest average amount of
Kjeldahl-N and were statistically identical to the control fish. Fish
receiving 21.5% SCP had a slightly lower Kjeldahl-N concentration. Fish
fed the 43% SCP diet also contained the highest amount of ash while the
fish receiving the 21.5% diet had the lowest ash content and all diets
resulted in fish with identical fat contents. These promising results
show that utilizing the world's massive quantities of food-processing
byproducts can result in significant benefits to aquaculture operations.

[0150] A wastewater stream having a BOD level of 5000 mg/L (no anaerobic
pretreatment) was introduced at a rate of 3 gallons per minute into an
8800 gallon continuously stirred tank reactor (CSTR) containing a mixed
community of unidentified bacteria obtained from the aerobic basin of a
wastewater treatment serving a brewery. Activated sludge was not returned
to the aerobic basin so the hydraulic residence time (HRT) of
approximately 2 days equaled the MCRT. The microorganisms were fed excess
nitrogen and phosphorus in the form of urea and phosphoric acid,
respectively, as well as an aqueous mixture of micronutrient metals as
described herein. The micronutrients consisted of soluble aluminum
compounds at a concentration of <1% by weight of the final mixture,
boric acid at a concentration of <1% by weight of the final mixture,
citric acid at a concentration of <1% by weight of the final mixture,
cobalt sulfate at a concentration of 1-5% by weight of the final mixture,
copper sulfate at a concentration of 1-5% by weight of the final mixture,
ferric chloride at a concentration of 1-5% by weight of the final
mixture, manganese sulfate at a concentration of 1-5% by weight of the
final mixture, nickel chloride at a concentration of 1-5% by weight of
the final mixture, sodium molybdate at a concentration of 1-5% by weight
of the final mixture, yeast extract at a concentration of <1% by
weight of the final mixture, and zinc sulfate at a concentration of 1-5%
by weight of the final mixture. This micronutrient mixture was added at a
dosage equivalent to 1 μL per 250 mL of wastewater delivered to the
aerobic tank. Process operating conditions therefore provided an MWRT
value of approximately 2.5 days, and MWRT-MCRT of approximately 0.5 days.
Biomass was removed from the CSTR and dewatered in a high-speed
continuous centrifuge at 6000 gravities to a solids content of
approximately 6%. The dewatered biomass was then dried at 68° C.
for about 12 hours and bagged to prevent re-adsorption of moisture. The
single cell protein prepared by the above process had the following
properties: